Non-ionic compound, resin, resist composition and method for producing resist pattern

ABSTRACT

A compound which is non-ionic compound, the compound has a group represented by formula (Ia): 
     
       
         
         
             
             
         
       
     
     wherein R 2  represents a group having a C 3  to C 18  alicyclic hydrocarbon group where a methylene group may be replaced by an oxygen atom or a carbonyl group, Rf 1  and Rf 2  each independently represent a C 1  to C 4  perfluoroalkyl group, and * represents a binding site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Application No. 2014-238552filed on Nov. 26, 2014. The entire disclosures of Japanese ApplicationNo. 2014-238552 is incorporated hereinto by reference.

BACKGROUND

1. Field of the Invention

The disclosure relates to a non-ionic compound, a resin, a resistcomposition and a method for producing resist pattern.

2. Related Art

A resist composition containing a resin having structural units below isdescribed in Patent document of JP2011-132273A.

SUMMARY

The disclosure provides following inventions of <1> to <11>.

<1> A compound which is non-ionic compound,

the compound having a group represented by formula (Ia):

wherein R² represents a group having a C₃ to C₁₈ alicyclic hydrocarbongroup where a methylene group may be replaced by an oxygen atom or acarbonyl group,

Rf¹ and Rf² each independently represent a C₁ to C₄ perfluoroalkylgroup, and

* represents a binding site.

<2> The compound according to <1>, which is represented by formula (I):

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom,

R² represents a group having a C₃ to C₁₈ alicyclic hydrocarbon groupwhere a methylene group may be replaced by an oxygen atom or a carbonylgroup,

Rf¹ and Rf² each independently represent a C₁ to C₄ perfluoroalkylgroup,

A¹ represents a single bond, a C₁ to C₆ alkanediyl group or**-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-,

** represents a binding site to an oxygen atom,

A², A³ and A⁴ each independently represent a C₁ to C₆ alkanediyl group,

X¹ and X² each independently represent —O—, —CO—O— or —O—CO—,

a represents 0 or 1, and

b represents 0 or 1.

<3> The compound according to <1> or <2>, wherein

R² is a group having a C₃ to C₁₈ alicyclic hydrocarbon group

<4> The compound according to any one of <1> to <3>, wherein

R² is a group having an adamantyl group where a methylene group may bereplaced by an oxygen atom or a carbonyl group, or a group having acyclohexyl group where a methylene group may be replaced by an oxygenatom or a carbonyl group.

<5> The compound according to any one of <1> to <4>, wherein

R² is an adamantyl group or a cyclohexyl group.

<6> The compound according to any one of <2> to <5>, wherein

A¹ is a C₁ to C₆ alkanediyl group or **-A²-O—CO—.

<7> A resin having a structural unit derived from the compound accordingto any one of <1> to <6>.

<8> A resist composition containing

the resin according to <7>,

a resin having an acid-labile group, and

an acid generator:

<9> A resist composition containing

the resin consisting of the structural unit derived from the compoundaccording to any one of <1> to <6>,

a resin having an acid-labile group, and

an acid generator:

<10> The resist composition according to <8> containing the resinfurther having a structural unit represented by formula (a5-1):

wherein, R⁵¹ represents a hydrogen atom or a methyl group,

R⁵² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogenatom may be replaced by a C₁ to C₈ aliphatic hydrocarbon group or ahydroxy group, provided that the carbon atom directly bonded to L⁵¹ hasno aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced, and

L⁵¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group.

<11> The resist composition according to any one of <8> to <10>, furthercontaining a salt which generates an acid weaker in acidity than an acidgenerated from the acid generator.

<12> A method for producing a resist pattern includes steps (1) to (5);

(1) applying the resist composition according to any one of <8> to <11>onto a substrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

DETAILED DESCRIPTION OF THE EMBODIMENT

In the specification, the term “(meth)acrylic monomer” means a monomerhaving a structure of “CH₂═CH—CO—” or “CH₂═C(CH₃)—CO—”, as well as“(meth)acrylate” and “(meth)acrylic acid” mean “an acrylate ormethacrylate” and “an acrylic acid or methacrylic acid,” respectively.Herein, chain structure groups include those having a linear structureand those having a branched structure. The indefinite articles “a” and“an” are taken as the same meaning as “one or more”.

The term “solid components” means components other than solvents in aresist composition.

<Compound (Ia)>

The compound of the disclosure, which is sometimes referred to as“compound (Ia)”, is a non-ionic compound having a group represented byformula (Ia);

wherein R² represents a group having a C₃ to C₁₈ alicyclic hydrocarbongroup where a methylene group may be replaced by an oxygen atom or acarbonyl group,

Rf¹ and Rf² each independently represent a C_(j) to C₄ perfluoroalkylgroup, and

* represents a binding site.

Herein, the “group having a C₃ to C₁₈ alicyclic hydrocarbon group”includes a group consisting of the alicyclic hydrocarbon group as wellas a group composed of the alicyclic hydrocarbon group and another groupsuch as chain hydrocarbon group.

Examples of the alicyclic hydrocarbon group for R² include any ofmonocyclic- or polycyclic group. Examples of the monocyclic groupinclude cyclopentyl, cyclohexyl group, cycloheptyl and cyclooctylgroups. Examples of the polycyclic group include decahydronaphthyl,adamantyl and norbornyl groups.

The group having the alicyclic hydrocarbon group is preferably a C₃ toC₁₈ alicyclic hydrocarbon group. Specific examples of the group havingthe alicyclic hydrocarbon group include a group combined with analkanediyl group and an alicyclic hydrocarbon group substituted with analkyl group and a group combined with an alkanediyl group and analicyclic hydrocarbon group, preferably a —(CH₂)_(m)-adamantyl group anda —(CH₂)_(n)-cyclohexyl group. m and n each independently represent aninteger of 0 to 3.

Examples of the alkanediyl group include a liner alkanediyl group suchas methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as ethane-1,1-diyl, propane-1,2-diyl,butane-1,3-diyl, 2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,pentane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

Examples of the alicyclic hydrocarbon group substituted with an alkylgroup include methylcyclohexyl, dimethylcyclohexyl, methylnorbornyl,cyclohexylmethyl, adamantylmethyl and norbornylethyl groups.

In the group having a C₃ to C₁₈ alicyclic hydrocarbon group, a methylenegroup in the alicyclic hydrocarbon group may be replaced by an oxygenatom or a carbonyl group. Examples of the alicyclic hydrocarbon group inwhich a methylene group has been replaced by an oxygen atom or acarbonyl group include an adamantanone group, a cyclohexanone group, acyclopentanone group, an adamantanelactone group and a norbornanelactonegroup.

Example of the group represented by R² include preferably a group havinga cyclopentyl group, a group having a cyclohexyl group, a group havingan adamantyl group, a group having a norbornyl group, a group having anadamantanone group, a group having a cyclohexanone group, a group havinga cyclopentanone group, a group having an adamantanelactone group, agroup having a norbornanelactone group.

Among these, a group having a cyclohexyl group and a group having anadamantyl group are more preferred, a cyclohexyl group, an adamantylgroup and an adamantanone group are still more preferred, and acyclohexyl group and an adamantyl group are further still morepreferred.

Examples of the C₁ to C₄ perfluoroalkyl group for Rf¹ and Rf² includetrifluoromethyl, perfluoroethyl, perfluoropropyl and perfluorobutylgroups.

Rf¹ and Rf² are preferably a trifluoromethyl group.

<Compound (I)>

The non-ionic compound, which is the non-ionic compound having a grouprepresented by formula (Ia), is preferably a compound represented byformula (I), which is sometimes referred to as “compound (I)”:

wherein R², Rf¹ and Rf² represent the same meaning as defined above,

R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆ alkyl groupthat may have a halogen atom,

A¹ represents a single bond, a C₁ to C₆ alkanediyl group or**-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-,

** represents a binding site to an oxygen atom,

A², A³ and A⁴ each independently represent a C₁ to C₆ alkanediyl group,

X¹ and X² each independently represent —O—, —CO—O— or —O—CO—,

a represents 0 or 1, and

b represents 0 or 1.

Examples of the alkyl group for R¹ include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups,the alkyl group is preferably a C₁ to C₄ alkyl group, and morepreferably a methyl group or an ethyl group.

Examples of the halogen atom for R¹ include fluorine, chlorine, bromineor iodine atom.

Examples of the alkyl group that has a halogen atom for R¹ includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, perchloromethyl, perbromomethyl andperiodomethyl groups.

R¹ is preferably a hydrogen atom or a methyl group.

Examples of the alkanediyl group for A¹, A², A³ and A⁴ include a lineralkanediyl group such as methylene, ethylene, propane-1,3-diyl,butane-1,4-diyl, pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as ethane-1,1-diyl, propane-1,2-diyl,butane-1,3-diyl, 2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,pentane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

Examples of **-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)- include *^(*-)A²-O—,*^(*-)A²-CO—O—, *^(*-)A²-CO—O-A⁴-*^(*)-A²-O—CO—, *^(*)-A²-CO—O-A³-CO—O—,*^(*)-A²-CO—O-A³-CO—O-A⁴-*^(*)-A²-O—CO-A³-O—, *^(*)-A²-O-A³-CO—O—,*^(*)-A²-CO—O-A³-O—CO—, *^(*)-A²-O—CO-A³-O—CO—. Among these, **-A²-O— or*-A²-O—CO— is preferred. ** represents a bonding site to an oxygen atom.

A1, A2, A³ and A⁴ are preferably a C₂ to C₆ divalent alkanediyl group.

A¹ is preferably a C₁ to C₆ alkanediyl group or **-A²-X¹—, morepreferably a C₁ to C₆ alkanediyl group or **-A²-O—CO—, still morepreferably a C₂ to C₆ alkanediyl group, **—CH₂—O—CO— or **—C₂H₄—O—CO—,and further still more preferably a C₃ to C₆ alkanediyl group or**—C₂H₄—O—CO—.

Examples of the compound (I) include the compounds represented by thefollowing ones.

Examples of the compound (I) include those represented by the aboveformulae in which a methyl group corresponding to R¹ has been replacedby a hydrogen atom.

<Method for Producing the Compound (I)>

For example, the compound (I) can be obtained by reacting a compoundrepresented by formula (I-a) with a compound represented by formula(I-b) in presence of a basic catalyst in a solvent:

wherein R¹, R², Rf¹, Rf² and A¹ are as defined above.

Preferred examples of the solvent include chloroform, tetrahydrofuranand toluene.

Preferred examples of the basic catalyst include a basic catalyst suchas pyridine and dimethylaminopyridine.

Examples of the compound represented by the formula (I-a) includecompound represented by formula below which is available on the market.

Examples of the compound represented by the formula (I-b) include thecompounds represented by formulae below which are available on themarket.

The compound represented by formula (II-a), that is the compoundrepresented by formula (I) in which A¹ is **-A²-O—CO—, can be obtainedby reacting a compound represented by formula (II-c) with a compoundrepresented by formula (II-d) in presence of a catalyst in a solvent:

wherein R¹, A², Rf¹ and Rf² are as defined above.

Preferred examples of the solvent include chloroform, tetrahydrofuranand toluene.

Preferred examples of the catalyst include a basic catalyst such aspyridine and dimethylaminopyridine, and a known esterified catalyst suchas acid catalysts and carbodiimide catalysts. The basic catalyst and theknown esterified catalyst can be used as a catalyst for the reaction.

Examples of the compound represented by the formula (II-c) include thecompound represented by formula below which is available on the market.

Examples of the compound represented by the formula (II-d) include thecompound represented by formula below which is available on the market.

Examples of the carbodiimide catalyst include the salt represented byformula below which is available on the market.

<Resin (X)>

A resin of the disclosure has a structural unit derived from thecompound (Ia) or the compound (I) as described above, which is sometimesreferred to as “structural unit (I)” (which is sometimes referred to as“resin (X)”). The resin (X) may have one kind of the structural unit (I)or two or more of the structural units (I).

The resin (X) may consist of the structural units (I), and may furtherhave a structural unit other than the structural unit (I). Examples ofthe structural unit include a structural unit having a fluorine atom(which is sometimes referred to as “structural unit (a4)”), a structuralunit having a non-leaving hydrocarbon group (which is sometimes referredto as “structural unit (a5)”), a structural unit having an acid-labilegroup (which is sometimes referred to as “structural unit (a1)”) and astructural unit having no acid-labile group (which is sometimes referredto as “structural unit (s)”), as well as a structural unit derived froman known monomer in this art.

When the resin (X) further has a structural unit other than thestructural unit (I), the structural unit (a4) and/or the structural unit(a5) is preferred as the another structural unit.

<Structural Unit (a4)>

The structural unit (a4) has a structural unit represented by formula(a4-0).

In the formula (a4-0), R⁵ represents a hydrogen atom or a methyl group,

L⁵ represents a single bond or a C₁ to C₄ saturated aliphatichydrocarbon group,

L³ represents a C₁ to C₈ perfluoroalkanediyl group or a C₃ to C₁₂perfluorocycloalkanediyl group, and

R⁶ represents a hydrogen atom or a fluorine atom.

Examples of the saturated aliphatic hydrocarbon group for L⁵ include C₁to C₄ alkanediyl group, i.e., a liner alkanediyl group such asmethylene, ethylene, propane-1,3-diyl, butane-1,4-diyl; and a branchedalkanediyl group such as ethane-1,1-diyl, propane-1,2-diyl,butane-1,3-diyl, 2-methylpropane-1,3-diyl and 2-methylpropane-1,2-diylgroups.

L⁵ is preferably a single bond, a methylene or ethylene group, and morepreferably a single bond or a methylene group.

Examples of the perfluoroalkanediyl group for L³ includedifluoromethylene, perfluoroethylene, perfluoroethyl fluoromethylene,perfluoropropane-1,3-diyl, a perfluoropropane-1,2-diyl,perfluoropropane-2,2-diyl, perfluorobutane-1,4-diyl,perfluorobutane-2,2-diyl, perfluorobutane-1,2-diyl,perfluoropentane-1,5-diyl, perfluoropentane-2,2-diyl,perfluoropentane-3,3-diyl, perfluorohexane-1,6-diyl,perfluorohexane-2,2-diyl, perfluorohexane-3,3-diyl,perfluoroheptane-1,7-diyl, perfluoroheptane-2,2-diyl,perfluoroheptane-3,4-diyl, perfluoroheptane-4,4-diyl,perfluorooctane-1,8-diyl, perfluorooctane-2,2-diyl,perfluorooctane-3,3-diyl and perfluorooctane-4,4-diyl groups.

Examples of the perfluorocycloalkanediyl group for L³ includeperfluorocyclohexanediyl, perfluorocyclopentanediyl,perfluorocycloheptanediyl and perfluoroadamantanediyl groups.

L³ is preferably a C₁ to C₆ perfluoroalkanediyl group, more preferably aC₁ to C₃ perfluoroalkanediyl group.

Examples of the structural unit (a4-0) include the following ones.

Examples of the structural unit (a4-0) include those represented byformulae (a4-0-1) to (a4-0-16) in which a methyl group corresponding toR⁵ has been replaced by a hydrogen atom.

Examples of the structural unit (a4) include the structural unitsrepresented by formula (a4-1):

wherein R^(a41) represents a hydrogen atom or a methyl group,

R^(a42) represents an optionally substituted C₁ to C₂₀ hydrocarbon groupwhere a methylene group may be replaced by an oxygen atom or a carbonylgroup, and

A^(a41) represents a C₁ to C₆ alkanediyl group optionally substitutedwith a hydroxy group or a C₁ to C₆ alkoxy group, or a group representedby formula (a-g1),

wherein s represents 0 or 1,

A^(a42) represents an optionally substituted C₁ to C₅ aliphatichydrocarbon group,

A^(a44) represents an optionally substituted C₁ to C₅ linear aliphatichydrocarbon group,

A^(a43) represents a single bond or an optionally substituted C₁ to C₅aliphatic hydrocarbon group, and

X^(a41) and X^(a42) each independently represent —O—, —CO—, —CO—O— or—O—CO—,

provided that the carbon atoms contained in A^(a42), A^(a43), A^(a44),X^(a41) and X^(a42) is 7 or less in total, and

* and ** represent a binding site, and * represents a binding site to—O—CO— R^(a42).

At least one of A^(a41) and R^(a42) preferably has a halogen atom as asubstituent.

The hydrocarbon group for R^(a42) may be a chain and a cyclic aliphatichydrocarbon groups, an aromatic hydrocarbon group and a combinationthereof.

The chain and the cyclic aliphatic hydrocarbon group may have acarbon-carbon unsaturated bond, and is preferably a chain and a cyclicsaturated aliphatic hydrocarbon group. Examples of the saturatedaliphatic hydrocarbon group include a liner or branched alkyl group, amonocyclic or polycyclic alicyclic hydrocarbon group, and an aliphatichydrocarbon group formed by combining the alkyl group and the alicyclichydrocarbon group.

Examples of the chain aliphatic hydrocarbon group include an alkyl groupsuch as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl and hexadecyl groups.

Examples of the alicyclic hydrocarbon group include a cycloalkyl groupsuch as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl groups; andpolycyclic hydrocarbon groups such as decahydronaphtyl, adamantyl andnorbornyl groups as well as groups below. * represents a binding site.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, biphenyl, phenanthryl and fluorenyl groups.

The hydrocarbon group for R^(a42) is preferably a chain and a cyclicaliphatic hydrocarbon groups, and a combination thereof. The hydrocarbongroup may have a carbon-carbon unsaturated bond, is preferably a chainand a cyclic saturated aliphatic hydrocarbon groups, and a combinationthereof.

Examples of the substituent of R^(a42) include a halogen atom or a grouprepresented by formula (a-g3).

Examples of the halogen atom include fluorine, chlorine, bromine oriodine atom, and preferably a fluorine atom:

*—X^(a43)-A^(a45)  (a-g3)

wherein X^(a43) represent an oxygen atom, a carbonyl group, acarbonyloxy group or an oxycarbonyl group,

A^(a45) represents a C₁ to C₁₇ aliphatic hydrocarbon group that has ahalogen atom, and

* represents a binding site.

Examples of the aliphatic hydrocarbon group for A^(a45) are the sameexamples as the group of R^(a42).

R^(a42) is preferably an aliphatic hydrocarbon group that may have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or an aliphatic hydrocarbon group having the group represented bythe formula (a-g3).

When R^(a42) is an aliphatic hydrocarbon group having a halogen atom, analiphatic hydrocarbon group having a fluorine atom is preferred, aperfluoroalkyl group or a perfulorocycloalkyl group are more preferred,a C₁ to C₆ perfluoroalkyl group is still more preferred, a C₁ to C₃perfluoroalkyl group is particularly preferred.

Examples of the perfluoroalkyl group include perfluoromethyl,perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl,perfluorohexyl, perfluoroheptyl and perfluorooctyl groups. Examples ofthe perfluorocycloalkyl group include perfluorocyclohexyl group.

When R^(a42) is an aliphatic hydrocarbon group having the grouprepresented by the formula (a-g3), the aliphatic hydrocarbon group haspreferably 15 or less, more preferably 12 or less of carbon atoms.R^(a42) has preferably one of the group represented by the formula(a-g3), when R^(a42) has a group represented by the formula (a-g3).

The aliphatic hydrocarbon group having the group represented by theformula (a-g3) is more preferably a group represented by formula (a-g2):

*-A^(a46)-X^(a44)-A^(a47)  (a-g2)

wherein A^(a46) represents a C₁ to C₁₇ linear or cyclic aliphatichydrocarbon group that may have a halogen atom,

X^(a44) represent a carbonyloxy group or an oxycarbonyl group,

A^(a47) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may havea halogen atom,

provided that the carbon atoms contained in A^(a46), X^(a44) and X^(a44)is 18 or less in total,

at least one of A^(a46) and A^(a47) has a halogen atom, and

* represents a binding site to a carbonyl group.

The aliphatic hydrocarbon group of A^(a46) has preferably 1 to 6, andmore preferably 1 to 3, of carbon atoms.

The aliphatic hydrocarbon group of A^(a47) has preferably 4 to 15, andmore preferably 5 to 12, of carbon atoms. A^(a47) is more preferably acyclohexyl group or an adamantyl group.

Preferred structure represented by the formula (a-g2),*-A^(a46)-X^(a47)-A^(a47), include the following ones.

Examples of the alkanediyl group for A^(a41) include a liner alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as propane-1,2-diyl, butan-1,3-diyl,2-methylpropane-1,2-diyl, 1-methylbutane-1,4-diyl,2-methylbutane-1,4-diyl groups.

A^(a41) is preferably a C₁ to C₄ alkanediyl group, more preferably a C₂to C₄ alkanediyl group, and still more preferably an ethylene group.

In the group represented by the formula (a-g1) (which is sometimesreferred to as “group (a-g1)”), examples of the aliphatic hydrocarbongroup for A^(a42), A^(a43) and A^(a44) include methylene, ethylene,propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,1-methylpropane-1,3-diyl, 2-methylpropane-1,3-diyl and2-methylpropane-1,2-diyl groups.

Examples of the substituent of the aliphatic hydrocarbon group forA^(a42), A^(a43) and A^(a44) include a hydroxy group and a C₁ to C₆alkoxy group.

s is preferably 0.

Examples of the group (a-g1) in which X^(a42) represents an oxygen atominclude the following ones. In the formula, * and ** each represent abinding site, and ** represents a binding site to —O—CO—R^(a42).

Examples of the group (a-g1) in which X^(a42) represents a carbonylgroup include the following ones.

Examples of the group (a-g1) in which X^(a42) represents a carbonyloxygroup include the following ones.

Examples of the group (a-g1) in which X^(a42) represents an oxycarbonylgroup include the following ones.

The structural unit represented by the formula (a4-1) is preferablystructural units represented by formula (a4-2) and formula (a4-3):

wherein R^(f1a) represents a hydrogen atom or a methyl group,

A^(f1) represent a C₁ to C₆ alkanediyl group, and

R^(f2a) represents a C₁ to C₁₀ hydrocarbon group that has a fluorineatom.

Examples of the alkanediyl group for A^(f1) include a liner alkanediylgroup such as methylene, ethylene, propane-1,3-diyl, propane-1,2-diyl,butane-1,4-diyl, pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as 1-methylpropane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,1-methylbutane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

The hydrocarbon group for R^(f2a) includes an aliphatic hydrocarbongroup and an aromatic hydrocarbon group. The aliphatic hydrocarbon groupincludes a chain and a cyclic groups, and a combination thereof. Thealiphatic hydrocarbon group is preferably an alkyl group and analicyclic hydrocarbon group.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and2-ethylhexyl groups.

Examples of the alicyclic hydrocarbon group include any of a monocyclicgroup and a polycyclic group. Examples of the monocyclic alicyclichydrocarbon group include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl groups.Examples of the polycyclic hydrocarbon groups includesdecahydronaphthyl, adamantyl, 2-alkyladamantane-2-yl,1-(adamantane-1-yl)alkane-1-yl, norbornyl, methylnorbornyl and isobornylgroups.

Examples of the hydrocarbon group having a fluorine atom for R^(f2a)include an alkyl group having a fluorine atom and an alicyclichydrocarbon group having a fluorine atom.

Specific examples of an alkyl group having a fluorine atom include afluorinated alkyl group such as difluoromethyl, trifluoromethyl,1,1-difluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl,perfluoroethyl, 1,1,2,2-tetrafluoropropyl, 1,1,2,2,3,3-hexafluoropropyl,perfluoroethylmethyl, 1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl,perfluoropropyl, 1-(trifluoromethyl)-2,2,2-trifluoroethyl,perfluoropropyl, 1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, perfluorobutyl,1,1-bis(trifluoro)methyl-2,2,2-trifluoroethyl, 2-(perfluoropropyl)ethyl,1,1,2,2,3,3,4,4-octafluoropentyl, perfluoropentyl,1,1,2,2,3,3,4,4,5,5-decafluoropentyl,1,1-bis(trifluoromethyl)2,2,3,3,3-pentafluoropropyl,2-(perfluorobutyl)ethyl, 1,1,2,2,3,3,4,4,5,5-decafluorohexyl,1,1,2,2,3,3,4,4,5,5,6,6-dodeca fluorohexyl, perfluoropentylmethyl andperfluorohexyl groups.

Examples of the alicyclic hydrocarbon group having a fluorine atominclude a fluorinated cycloalkyl group such as perfluorocyclohexyl andperfluoroadamantyl groups.

In the formula (a4-2), A^(f1) is preferably a C₂ to C₄ alkanediyl group,and more preferably an ethylene group.

R^(f2a) is preferably a C₁ to C₆ fluorinated alkyl group.

wherein R^(f11) represents a hydrogen atom or a methyl group,

-   -   A^(f11) represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ linear or alicyclic aliphatic hydrocarbongroup that may have a fluorine atom,

X^(f12) represents an oxycarbonyl group or a carbonyloxy group,

A^(f14) represents a C₁ to C₁₇ aliphatic hydrocarbon group that may havea fluorine atom, and

provided that at least one of A^(f13) and A^(f14) represents analiphatic hydrocarbon group having a fluorine atom.

Examples of the alkanediyl group for A^(f11) are the same examples asthe alkanediyl group of A^(f1).

Examples of the aliphatic hydrocarbon group for A^(f13) include any of adivalent linear or cyclic aliphatic hydrocarbon group, or a combinationthereof. The aliphatic hydrocarbon group may have a carbon-carbonunsaturated bond, and is preferably a saturated aliphatic hydrocarbongroup.

The aliphatic hydrocarbon group that may have a fluorine atom forA^(f13) is preferably the saturated aliphatic hydrocarbon group that mayhave a fluorine atom, and more preferably perfuloroalkandiyl group.

Examples of the divalent linear aliphatic hydrocarbon that may have afluorine atom include an alkanediyl group such as methylene, ethylene,propanediyl, butanediyl and pentanediyl groups; a perfluoroalkanediylgroup such as difluoromethylene, perfluoroethylene,perfluoropropanediyl, perfluorobutanediyl and perfluoropentanediylgroups.

The divalent cyclic aliphatic hydrocarbon group that may have a fluorineatom is any of monocyclic or polycyclic group.

Examples monocyclic aliphatic hydrocarbon group include cyclohexanediyland perfluorocyclohexanediyl groups.

Examples polycyclic aliphatic hydrocarbon group include adamantanediyl,norbornanediyl, and perfluoroadamantanediyl groups.

Examples of the aliphatic hydrocarbon group for A^(f14) include any of achain or a cyclic aliphatic hydrocarbon group, or a combination thereof.The aliphatic hydrocarbon group may have a carbon-carbon unsaturatedbond, and is preferably a saturated aliphatic hydrocarbon group.

The aliphatic hydrocarbon group that may have a fluorine atom of A^(f14)is preferably the saturated aliphatic hydrocarbon group that may have afluorine atom.

Examples of the chain aliphatic hydrocarbon group that may have ahalogen atom include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, pentyl, hexyl, perfluorohexyl,hepthyl, perfluoroheptyl, octyl and perfluorooctyl groups.

The cyclic aliphatic hydrocarbon group that may have a fluorine atom isa group including any of monocyclic or polycyclic group. Examples of thegroup including the monocyclic aliphatic hydrocarbon group includescyclopropylmethyl, cyclopropyl, cyclobutylmethyl, cyclopentyl,cyclohexyl and perfluorocyclohexyl groups. Examples of the groupincluding the polycyclic aliphatic hydrocarbon group includes adamantyl,adamantylmethyl, norbornyl, norbornylmethyl, perfluoroadamantyl andperfluoroadamantylmethyl groups.

In the formula (a4-3), A^(f11) is preferably an ethylene group.

The linear aliphatic hydrocarbon group for A^(n3) is preferably a C₁ toC₆ linear aliphatic hydrocarbon group, more preferably a C₂ to C₃ linearaliphatic hydrocarbon group.

The aliphatic hydrocarbon group of A^(f14) is preferably a C₃ to C₁₂aliphatic hydrocarbon group, more preferably a C₃ to C₁₀ aliphatichydrocarbon group. Among these, A^(f14) is preferably a group containinga C₃ to C₁₂ alicyclic hydrocarbon group, more preferablycyclopropylmethyl, cyclopentyl, cyclohexyl, norbornyl and adamantylgroups.

Examples of the structural unit (a4-2) include structural unitsrepresented by formula (a4-1-1) to formula (a4-1-22).

Examples of the structural unit (a4-3) include structural unitspresented by formula (a4-1′-1) to formula (A4-1′-22).

Examples of the structural unit (a4) include a structural unit presentedby formula (a4-4):

wherein R^(f21) represents a hydrogen atom or a methyl group,

A^(f21) represents —(CH₂)_(j1)—(CH₂)_(j2)—(CH₂)_(j3)— or—(CH₂)_(j4)—CO—O—(CH₂)_(j5)—,

j1 to j5 each independently represents an integer of 1 to 6, and

R^(f22) represents a C₁ to C₁₀ hydrocarbon group having a fluorine atom.

Examples of the hydrocarbon group having a fluorine atom for R^(f22) arethe same examples as the hydrocarbon group described in R^(f2) in theformula (a4-2). R^(f22) is preferably a C₁ to C₁₀ alkyl group having afluorine atom or a C₃ to C₁₀ alicyclic hydrocarbon group having afluorine atom, more preferably a C₁ to C₁₀ alkyl group having a fluorineatom, and still more preferably a C₁ to C₆ alkyl group having a fluorineatom.

In the formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, morepreferably a methylene group or an ethylene group, and still morepreferably a methylene group.

Examples of the structural unit represented by the formula (a4-4)include the following ones.

<Structural Unit (a5)>

Examples of the non-leaving hydrocarbon group in the structural unit(a5) include a liner or branched, or a cyclic hydrocarbon group. Amongthese, the structural unit (a5) is preferably a structural unitrepresented by formula (a5-1), which is sometimes referred to as“structural unit (a5-1)”;

wherein R⁵¹ represents a hydrogen atom or a methyl group,

R⁵² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogenatom may be replaced by a C₁ to C₈ aliphatic hydrocarbon group or ahydroxy group, provided that the carbon atom directly bonded to L⁵¹ hasno aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced, and

L⁵¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group.

Examples of the alicyclic hydrocarbon group for R⁵² include any one of amonocyclic group or a polycyclic group. Examples of the monocyclicalicyclic hydrocarbon group include cyclopropyl, cyclobutyl, cyclopentyland cyclohexyl groups. Examples of the polycyclic hydrocarbon groupinclude adamantyl and norbornyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group include an alkylgroup such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octylgroups.

Examples of the alicyclic hydrocarbon group having a substituent for R⁵²include 3-hydroxyadamantyl group and 3-methyladamantyl group.

R⁵² is preferably an unsubstituted C₃ to C₁₈ alicyclic hydrocarbongroup, and more preferably an adamantyl, norbornyl or cyclohexyl group.

Examples of the divalent saturated hydrocarbon group for L⁵¹ include adivalent saturated aliphatic hydrocarbon group and a divalent saturatedalicyclic hydrocarbon group, and a divalent saturated aliphatichydrocarbon group is preferred.

Examples of the divalent saturated aliphatic hydrocarbon group includean alkanediyl such as methylene, ethylene, propanediyl, butanediyl andpentanediyl.

Examples of the divalent saturated alicyclic hydrocarbon group includeany of a monocyclic group and a polycyclic group. Examples of themonocyclic group include cycloalkanediyl group such as cyclopentanediyland cyclohexanediyl groups. Examples of the polycyclic group includeadamantanediyl and norbornanediyl groups.

Examples of the saturated hydrocarbon group in which a methylene grouphas been replaced by an oxygen atom or a carbonyl group include groupsrepresented by formula (L1-1) to formula (L1-4). In formula (L1-1) toformula (L1-4), * represents a binding site to an oxygen atom.

In the formulae, X^(X1) represents an oxycarbonyl group or a carbonyloxygroup,

L^(X1) represents a C₁ to C₁₆ divalent saturated aliphatic hydrocarbongroup,

L^(X2) represents a single bond or a C₁ to C₁₅ divalent saturatedaliphatic hydrocarbon group,

provided that the carbon atoms contained in L^(X1) and L^(X2) is 16 orless in total;

L^(X3) represents a single bond or a C₁ to C₁₇ divalent saturatedaliphatic hydrocarbon group,

L^(X4) represents a single bond or a C₁ to C₁₆ divalent saturatedaliphatic hydrocarbon group,

provided that the carbon atoms contained in L^(X3) and L^(X4) is 17 orless in total;

L^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L^(X6) and L^(X7) each independently represent a single bond or a C₁ toC₁₄ divalent saturated aliphatic hydrocarbon group,

provided that the carbon atoms contained in L^(X5), L^(X6) and L^(X7) is15 or less in total;

L^(X8) and L^(X9) each independently represent a single bond or a C₁ toC₁₂ divalent saturated aliphatic hydrocarbon group,

W^(X1) represents a C₃ to C₁₅ divalent saturated alicyclic hydrocarbongroup,

provided that the carbon atoms contained in L^(X8), L^(X9) and W^(X1) is15 or less in total.

L^(X1) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an an ethylene group.

L^(X2) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond.

L^(X3) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup.

L^(X4) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X5) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene group or an ethylene group.

L^(X6) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a methylene group or anethylene group.

L^(X7) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X8) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond or amethylene group.

L^(X9) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond or amethylene group.

W^(X1) is preferably a C₃ to C₁₀ divalent saturated alicyclichydrocarbon group, and more preferably a cyclohexanediyl oradamantanediyl group.

Examples of the group represented by the formula (L1-1) include thefollowing ones.

Examples of the group represented by the formula (L1-2) include thefollowing ones.

Examples of the group represented by the formula (L1-3) include thefollowing ones.

Examples of the group represented by the formula (L1-4) include thefollowing ones.

L⁵¹ is preferably a single bond, the C₁ to C₈ divalent saturatedhydrocarbon group or the group represented by the formula (L1-1), morepreferably a single bond, the C₁ to C₆ divalent saturated hydrocarbongroup or the group represented by the formula (L1-1).

Examples of the structural unit (a5-1) include the following ones.

Examples of the structural units (a5-1) include those represented byformulae (a5-1-1) to (a5-1-18) in which a methyl group corresponding toR⁵¹ has been replaced by a hydrogen atom.

The proportion of the structural unit (I) is preferably 10 to 100% bymole, more preferably 20 to 100% by mole, still more preferably 30 to100% by mole, with respect to the total structural units (100% by mole)of the resin (X).

When the resin (X) further has the structural unit (a4), the proportionthereof is preferably 5 to 90% by mole, more preferably 10 to 80% bymole, still more preferably 15 to 70% by mole, particularly preferably20 to 50% by mole, with respect to the total structural units (100% bymole) of the resin (X).

When the resin (X) further has the structural unit (a5), the proportionthereof is preferably 5 to 90% by mole, more preferably 10 to 80% bymole, still more preferably 15 to 70% by mole, particularly preferably20 to 50% by mole, with respect to the total structural units (100% bymole) of the resin (X).

The resin (X) can be produced by a known polymerization method, forexample, radical polymerization method, using one or more species ofmonomers inducing the structural units as described above. Theproportion of the structural unit in the resin (X) can be adjusted bychanging the amount of a monomer used in polymerization.

The weight average molecular weight of the resin (X) is preferably 6,000or more (more preferably 7,000 or more), and 80,000 or less (morepreferably 60,000 or less). In the present specification, the weightaverage molecular weight is a value determined by gel permeationchromatography using polystyrene as the standard product. The detailedcondition of this analysis is described in Examples.

<Resist Composition>

The resist composition of the disclosure contains the resin (X), a resinhaving an acid-labile group (which is sometimes referred to as “resin(A)”) and an acid generator (which is sometimes referred to as “acidgenerator (B)”).

The resist composition preferably further contains a quencher (which issometimes referred to as “quencher (C)”) or a solvent (which issometimes referred to as “solvent (E)”), more preferably furthercontains the quencher (C) and the solvent (E).

<Resin (A)>

The resin (A) has a structural unit having an acid-labile group (whichis structural unit (a1)). The resin (A) preferably has a structural unitother than the structural unit (a1). Examples of the structural unitother than the structural unit (a1) include a structural unit having noacid-labile group (which is structural unit (s)), a structural unitother than the structural unit (a1) and the structural unit (s) (whichis sometimes referred to as “structural unit (t)”), as well as thestructural unit derived from an known monomer in this art.

<Structural Unit (a1)>

The structural unit (a1) is derived from a monomer having an acid-labilegroup (which is sometimes referred to as “monomer (a1)”). Here the“acid-labile group” means a group having a leaving group which isdetached by contacting with an acid resulting in forming a hydrophilicgroup such as a hydroxy or carboxy group.

In the resin (A), the acid-labile group contained in the structural unit(a1) is preferably the following group (1) and/or group (2):

wherein R^(a1) to R^(a3) each independently represent a C₁ to C₈ alkylgroup, a C₃ to C₂₀ alicyclic hydrocarbon group or a combination thereof,or R^(a1) and R^(a2) may be bonded together with a carbon atom bondedthereto to form a C₃ to C₂₀ divalent hydrocarbon group;

na represents an integer of 0 or 1; and

* represents a binding site;

wherein R^(a1′) and R^(a2′) each independently represent a hydrogen atomor a C₁ to C₁₂ hydrocarbon group, R^(a3′) represents a C₁ to C₂₀hydrocarbon group, or R^(a2′) and R^(a3′) may be bonded together with acarbon atom and X bonded thereto to form a divalent C₃ to C₂₀ (or 4 to21-membered) heterocyclic group, and a methylene group contained in thehydrocarbon group or the divalent heterocyclic group may be replaced byan oxygen atom or a sulfur atom;

X represents —O— or —S—; and

* represents a binding site.

Examples of the alkyl group for R^(a1) to R^(a3) include methyl, ethyl,propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group for R^(a1) to R^(a3) includemonocyclic groups such as a cycloalkyl group, i.e., cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl groups; and polycyclic groups suchas decahydronaphtyl, adamantyl and norbornyl groups as well as thefollowing groups. In each of the formulae, * represents a binding site.

The carbon atoms of the alicyclic hydrocarbon group for R^(a1) to R^(a3)is preferably 3 to 16.

Examples of groups combining the alkyl group and the alicyclichydrocarbon group include methyl cyclohexyl, dimethyl cyclohexyl, methylnorbornyl and methyl adamantly, cyclohexylmethyl, methylcyclohexylmethyl, adamantylmethyl and norbornylmetyl groups.

na is preferably 0.

When R^(a1) and R^(a2) is bonded together to form a divalent hydrocarbongroup, examples of the group —C(R^(a1))(R^(a2))(R^(a3)) include thefollowing groups. The carbon atoms of the divalent hydrocarbon group ispreferably 3 to 12. In each of the formulae, * represent a binding siteto —O—.

In each formula, R^(a3) is as defined above.

Specific examples of the group represented by the formula (1) include,for example,

1,1-dialkylalkoxycarbonyl group (a group in which R^(a1) to R^(a3) arealkyl groups, preferably tert-butoxycarbonyl group, in the formula (1)),

2-alkyladamantane-2-yloxycarbonyl group (a group in which R^(a1), R^(a2)and a carbon atom form adamantyl group, and R^(a3) is alkyl group, inthe formula (1)), and

1-(adamantane-1-yl)-1-alkylalkoxycarbonyl group (a group in which R^(a1)and R^(a2) are alkyl group, and R^(a3) is adamantyl group, in theformula (1)).

The hydrocarbon group for R^(a1′) to R^(a3′) includes any of an alkylgroup, an alicyclic hydrocarbon group, an aromatic hydrocarbon group anda group formed by combining thereof.

Examples of the alkyl group and the alicyclic hydrocarbon group are thesame examples as described above.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the divalent heterocyclic group formed by bonding withR^(ar) and R^(a3′) with a carbon atom and X bonded thereto include thefollowing groups.

In each formula, R^(a1′) and X are as defined above.

At least one of R^(a1′) and R^(a2′) is preferably a hydrogen atom.

Specific examples of the group represented by the formula (2) includethe following groups. In each of the formulae, * represents a bindingsite.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylenically unsaturated bond, and more preferably a (meth)acrylicmonomer having an acid-labile group.

Among the (meth)acrylic monomer having an acid-labile group, a monomerhaving a C₅ to C₂₀ alicyclic hydrocarbon group is preferred. When aresin (A) including a structural unit derived from a monomer (a1) havinga bulky structure such as the alicyclic hydrocarbon group is used for aresist composition, the resist composition having excellent resolutiontends to be obtained.

In the resin (A), the total proportion of the structural units (a1) ispreferably 30 to 90% by mole, preferably 35 to 85% by mole, and morepreferably 40 to 80% by mole, with respect to the total structural units(100% by mole) of the resin (A).

Examples of a structural unit derived from the (meth)acrylic monomerhaving the group represented by the formula (1) preferably includestructural units represented by formula (a1-0), formula (a1-1) andformula (a1-2) below. These may be used as a single structural unit oras a combination of two or more structural units. The structural unitrepresented by formula (a1-0), the structural unit represented byformula (a1-1) and a structural unit represented by formula (a1-2) aresometimes referred to as “structural unit (a1-0)”, “structural unit(a1-1)” and “structural unit (a1-2)”), respectively, and monomersinducing the structural unit (a1-0), the structural unit (a1-1) and thestructural unit (a1-2) are sometimes referred to as “monomer (a1-0)”,“monomer (a1-1)” and “monomer (a1-2)”), respectively:

wherein L^(a01) represents —O— or *—O—(CH₂)_(k01)—CO—O—,

k01 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a02) represents a hydrogen atom or a methyl group, and

R^(a02), R^(a03) and R^(a04) each independently represent a C₁ to C₈alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a combinationthereof.

L^(a01) is preferably an —O— or *—O—(CH₂)_(ko1)—CO—O— in which k01 ispreferably an integer of 1 to 4, more preferably an integer of 1, morepreferably an —O—.

Examples of the alkyl group and an alicyclic hydrocarbon group, and thecombination thereof for R^(a02), R^(a03) and R^(a04) are the sameexamples as the group described in R^(a1) to R^(a3) in the formula (1).

The alkyl group of R^(a02), R^(a03) and R^(a04) is preferably a C₁ to C₆alkyl group.

The alicyclic hydrocarbon group of R^(a02), R^(a03) and R^(a04) ispreferably a C₃ to C₈ alicyclic hydrocarbon group, more preferably a C₃to C₆ alicyclic hydrocarbon group.

The group formed by combining the alkyl group and the alicyclichydrocarbon group has preferably 18 or less of carbon atom. Examples ofthose groups include methylcyclohexyl, dimethylcyclohexyl,methylnorbornyl, methyladamantyl, cyclohexylmethl, methylcyclohexylmethyladamantylmethyl, adamantylmethyl and norbornylmethyl groups.

R^(a02) and R^(a03) is preferably a C₁ to C₆ alkyl group, morepreferably a methyl group or an ethyl group.

R^(a04) is preferably a C₁ to C₆ alkyl group or a C₅ to C₁₂ alicyclichydrocarbon group, more preferably methyl, ethyl, cyclohexyl oradamantyl group.

In each formula, L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—,

k1 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a4) and R^(a5) each independently represent a hydrogen atom or amethyl group,

R^(a6) and R^(a7) each independently represent a C₁ to C₈ alkyl group, aC₃ to C₁₈ alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

L^(a1) and L^(a2) are preferably —O— or *—O—(CH₂)_(k1′)—CO—O— in whichk1′ represents an integer of 1 to 4 and more preferably 1, and stillmore preferably —O—.

R^(a4) andR^(a5) are preferably a methyl group.

Examples of the alkyl group and an alicyclic hydrocarbon group, and thecombination thereof for R^(a6) and R^(a7) are the same examples as thegroup described in R^(a1) to R^(a3) in the formula (1).

The alkyl group of R^(a6) and R^(a7) is preferably a C₁ to C₆ alkylgroup.

The alicyclic hydrocarbon group of R^(a6) and R^(a7) is preferably a C₃to C₈ alicyclic hydrocarbon group, and more preferably a C₃ to C₆alicyclic hydrocarbon group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1.

Examples of the structural unit (a1-0) preferably include structuralunits represented by formula (a1-0-1) to formula (a1-0-12), and morepreferably structural units represented by formula (a1-0-1) to formula(a1-0-10) below.

Examples of the structural units (a1-0) include those represented by theabove formulae in which a methyl group corresponding to R^(a01) has beenreplaced by a hydrogen atom.

Examples of the monomer (a1-1) include monomers described in JP2010-204646A. Among these, the monomers are preferably monomersrepresented by formula (a1-1-1) to formula (a1-1-8), and more preferablymonomers represented by formula (a1-1-1) to formula (a1-1-4) below.

Examples of the monomer (a1-2) include1-methylcyclopentane-1-yl(meth)acrylate,1-ethylcyclopentane-1-yl(meth)acrylate,1-methylcyclohexane-1-yl(meth)acrylate,1-ethylcyclohexane-1-yl(meth)acrylate,1-ethylcycloheptane-1-yl(meth)acrylate,1-ethylcyclooctane-1-yl(meth)acrylate,1-isopropylcyclopentane-1-yl(meth)acrylate and1-isopropylcyclohexane-1-yl(meth)acrylate. Among these, the monomers arepreferably monomers represented by formula (a1-2-1) to formula(a1-2-12), and more preferably monomers represented by formula (a1-2-3),formula (a1-2-4), formula (a1-2-9) and formula (a1-2-10), and still morepreferably monomer represented by formula (a1-2-3) and formula (a1-2-9)below.

When the resin (A) has the structural unit (a1-0) and/or the structuralunit (a1-1) and/or the structural unit (a1-2), the total proportionthereof is generally 10 to 95% by mole, preferably 15 to 90% by mole,and more preferably 20 to 85% by mole, with respect to the totalstructural units (100% by mole) of the resin (A).

Further, examples of the structural unit (a1) having the group (1)include a structural unit presented by formula (a1-3). The structuralunit represented by formula (a1-3) is sometimes referred to as“structural unit (a1-3)”. The monomer from which the structural unit(a1-3) is derived is sometimes referred to as “monomer (a1-3)”.

In the formula, R^(a9) represents a carboxy group, a cyano group, a—COOR^(a13), a hydrogen atom or a C₁ to C₃ aliphatic hydrocarbon groupthat may have a hydroxy group,

R^(a13) represents a C₁ to C₈ aliphatic hydrocarbon group, a C₃ to C₂₀alicyclic hydrocarbon group or a group formed by combining thereof, ahydrogen atom contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by a hydroxy group, amethylene group contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by an oxygen atom or acarbonyl group, and

R^(a10), R^(a11) and R^(a12) each independently represent a C₁ to C₈alkyl group, a C₃ to C₂₀ alicyclic hydrocarbon group or a group formedby combining thereof, or R^(a10) and R^(a11) may be bonded together witha carbon atom bonded thereto to form a C₂ to C₂₀ divalent hydrocarbongroup.

Here, examples of —COOR^(a13) group include a group in which a carbonylgroup is bonded to the alkoxy group, such as methoxycarbonyl andethoxycarbonyl groups.

Examples of the aliphatic hydrocarbon group that may have a hydroxygroup for R^(a9) include methyl, ethyl, propyl, hydroxymethy and2-hydroxyethyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group for R^(a13) includemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the C₃ to C₂₀ alicyclic hydrocarbon group for R^(a13)include cyclopentyl, cyclopropyl, adamantyl, adamantylmetyl,1-(adamantyl-1-yl)-methylethyl, 2-oxo-oxolane-3-yl, 2-oxo-oxolane-4-ylgroups.

Examples of the alkyl group for R^(a10) to R^(a12) include methyl,ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group for R^(a10) and R^(a12)include monocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl groups; andpolycyclic groups such as decahydronaphtyl, adamantyl,2-alkyl-2-adamantyl, 1-(adamantane-1-yl)alkane-1-yl, norbornyl, methylnorbornyl and isobornyl groups.

When R^(a10) and R^(a11) are bonded together with a carbon atom bondedthereto to form a divalent hydrocarbon group, examples of thegroup-C(R^(a10))(R^(a11))(R^(a12)) include the following groups.

In each formula, R^(a12) is as defined above.

Examples of the monomer (a1-3) include tert-butyl5-norbornene-2-carboxylate, 1-cyclohexyl-1-methylethyl5-norbornene-2-carboxylate, 1-methylcyclohexyl5-norbornene-2-carboxylate, 2-methy-2-adamantane-2-yl5-norbornene-2-carboxylate, 2-ethyl-2-adamantane-2-yl5-norbornene-2-carboxylate, 1-(4-methycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-(4-hydroxycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-methyl-(4-oxocyclohexyl)-1-ethyl5-norbornene-2-carboxylate, and 1-(1-adamantane-1-yl)-1-methylethyl5-norbornene-2-carboxylate.

The resin (A) having the structural unit (a1-3) can improve theresolution of the obtained resist composition because it has a bulkystructure, and also can improve a dry-etching tolerance of the obtainedresist composition because of incorporated a rigid norbornene ring intoa main chain of the resin (A).

When the resin (A) has the structural unit (a1-3), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, with respect to the total structural units constituting the resin(A) (100% by mole).

Examples of a structural unit (a1) having the group (2) include astructural unit represented by formula (a1-4). The structural unit issometimes referred to as “structural unit (a1-4)”.

In the formula, R^(a32) represents a hydrogen atom, a halogen atom or aC₁ to C₆ alkyl group that may have a halogen atom,

R^(a33) in each occurrence independently represent a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group,

1a represents an integer 0 to 4,

R^(a34) and R^(a35) each independently represent a hydrogen atom or a C₁to C₁₂ hydrocarbon group; and

R^(a36) represents a C₁ to C₂₀ hydrocarbon group, or R^(a35) and R^(a36)may be bonded together with a C—O bonded thereto to form a divalent C₃to C₂₀ heterocyclic group, and a methylene group contained in thehydrocarbon group or the divalent heterocyclic group may be replaced byan oxygen atom or a sulfur atom.

Examples of the alkyl group for R^(a32) and R^(a33) include methyl,ethyl, propyl, isopropyl, butyl, pentyl and hexyl groups. The alkylgroup is preferably a C₁ to C₄ alkyl group, and more preferably a methylgroup or an ethyl group, and still more preferably a methyl group.

Examples of the halogen atom for R^(a32) and R^(a33) include a fluorine,chlorine, bromine and iodine atoms.

Examples of the alkyl group that may have a halogen atom includetrifluoromethyl, difluoromethyl, methyl, perfluoroethyl,1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl,1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

Examples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy and hexyloxy groups. The alkoxy group is preferably a C₁ to C₄alkoxy group, more preferably a methoxy group or an ethoxy group, andstill more preferably methoxy group.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the acyloxy group include acetyloxy, propionyloxy andbutyryloxy groups.

Examples of the hydrocarbon group for R^(a34) and R^(a35) are the sameexamples as described in R^(a1′) to R^(a2′) in the formula (2).

Examples of hydrocarbon group for R^(a36) include a C₁ to C₁₈ alkylgroup, a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a group formed by combining thereof.

In the formula (a1-4), R^(a32) is preferably a hydrogen atom.

R^(a33) is preferably a C₁ to C₄ alkoxy group, more preferably a methoxygroup or an ethoxy group, and still more preferably a methoxy group.

1a is preferably 0 or 1, and more preferably 0.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a C₁ to C₁₂ hydrocarbon group, and more preferablya methyl group or an ethyl group.

The hydrocarbon group for R^(a36) is preferably a C₁ to C₁₈ alkyl group,a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a combination thereof, and more preferably a C₁ toC₁₈ alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a C₇ to C₁₈aralkyl group. The alkyl group and the alicyclic hydrocarbon group forR^(a36) are preferably unsubstituted. When the aromatic hydrocarbongroup of R^(a36) has a substituent, the substituent is preferably a C₆to C₁₀ aryloxy group.

Examples of the monomer from which the structural unit (a1-4) is derivedinclude monomers described in JP 2010-204646A. Among these, the monomersare preferably the following monomers represented by formula (a1-4-1) toformula (a1-4-8), and more preferably monomers represented by formula(a1-4-1) to formula (a1-4-5).

When the resin (A) has the structural unit (a1-4), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, with respect to the total structural units constituting the resin(A) (100% by mole).

Examples of the structural unit having an acid-labile group include astructural unit represented by formula (a1-5). The structural unit issometimes referred to as “structural unit (a1-5)”.

In the formula (a1-5), R^(a5) represents a hydrogen atom, a halogen atomor a C₁ to C₆ alkyl group that may have a halogen atom,

Z^(a1) represent a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-,

h3 represents an integer of 1 to 4,

* represents a binding site to L⁵¹,

L⁵¹, L⁵², L⁵³ and L⁵⁴ each independently represent —O— or —S—,

s1 represents an integer of 1 to 3, and

s1′ represents an integer of 0 to 3.

In the formula (a1-5), R^(a5) is preferably a hydrogen atom, a methylgroup or a trifluoromethyl group;

L⁵¹ is preferably —O—;

L⁵² and L⁵³ are independently preferably —O— or —S—, and more preferablyone is —O— and another is —S—.

s1 is preferably 1;

s1′ is preferably an integer of 0 to 2;

Z^(a1) is preferably a single bond or *—CH₂—CO—O—. * represents abinding site to L⁵¹.

Examples of a monomer from which the structural unit (a1-5) is derivedinclude a monomer described in JP 2010-61117A. Among these, the monomersare preferably monomers represented by formula (a1-5-1) to formula(a1-5-4), and more preferably monomers represented by formula (a1-5-1)to formula (a1-5-2) below.

When the resin (A) has the structural unit (a1-5), the proportionthereof is preferably 1% by mole to 50% by mole, more preferably 3% bymole to 45% by mole, and still more preferably 5% by mole to 40% bymole, with respect to the total structural units (100% by mole)constituting the resin (A).

The resin (A) has, as the structural unit (a1), preferably at least one,more preferably two or more structural units selected from thestructural unit (a1-0), the structural unit (a1-1), the structural unit(a1-2) and the structural unit (a1-5), still more preferably thestructural unit (a1-1) or the structural unit (a1-2), a combination ofthe structural unit (a1-1) and the structural unit (a1-2), a combinationof the structural unit (a1-1) and the structural unit (a1-5), acombination of the structural unit (a1-1) and the structural unit(a1-0), a combination of the structural unit (a1-2) and the structuralunit (a1-0), a combination of the structural unit (a1-5) and thestructural unit (a1-0), a combination of the structural unit (a1-0), thestructural unit (a1-1) and the structural unit (a1-2), a combination ofthe structural unit (a1-0), the structural unit (a1-1) and thestructural unit (a1-5), and further still preferably a combination ofthe structural unit (a1-1) and the structural unit (a1-2), a combinationof the structural unit (a1-1) and the structural unit (a1-5).

<Structural Unit (s)>

The structural unit (s) is derived from a monomer having no acid-labilegroup (which monomer is sometimes referred to as “monomer (s)”).

As the monomer (s) from which the structural unit (s) is derived, aknown monomer having no acid-labile group can be used.

As the structural unit (s), a structural unit having a hydroxy group ora lactone ring but having no acid-labile group is preferred. When aresin having the structural unit derived from a structural unit having ahydroxy group but having no acid-labile group (such structural unit issometimes referred to as “structural unit (a2)”) and/or a structuralunit having a lactone ring but having no acid-labile group (suchstructural unit is sometimes referred to as “structural unit (a3)”) isused, the adhesiveness of resist to a substrate and resolution of resistpattern tend to be improved.

<Structural Unit (a2)>

The structural unit (a2) having a hydroxy group may be an alcoholichydroxy group or a phenolic hydroxy group.

When KrF excimer laser lithography (248 nm), or high-energy irradiationsuch as electron beam or EUV (extreme ultraviolet) is used for theresist composition, using the structural unit having a phenolic hydroxygroup as the structural unit (a2) is preferred.

When ArF excimer laser lithography (193 nm) is used, using thestructural unit having an alcoholic hydroxy group as the structural unit(a2) is preferred, and using the structural unit represented by formula(a2-1) is more preferred.

The structural unit (a2) may be used as a single structural unit or as acombination of two or more structural units.

When the resin (A) has the structural units (a2) having the hydroxygroup, the total proportion thereof is preferably 5% by mole to 95% bymole, more preferably 10% by mole to 80% by mole, and still morepreferably 15% by mole to 80% by mole, with respect to the totalstructural units (100% by mole) constituting the resin (A).

Examples of the structural unit (a2) having a phenolic hydroxy groupinclude a structural unit represented by formula (a2-0) (which issometimes referred to as “structural unit (a2-0)”).

wherein R^(a30) represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom,

R^(a31) in each occurrence independently represents a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group, and

ma represents an integer 0 to 4.

Examples of the alkyl group include methyl, ethyl, propyl, butyl,n-pentyl and n-hexyl groups.

Examples of the halogen atom include a chlorine atom, a fluorine atomand bromine atom.

Examples of the C₁ to C₆ alkyl group that may have a halogen atom forR^(a30) include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

R^(a30) is preferably a hydrogen atom or a C₁ to C₄ alkyl group, andmore preferably a hydrogen atom, a methyl group or an ethyl group, andstill more preferably a hydrogen atom or a methyl group.

Examples of the alkoxy group for R^(a31) include methoxy, ethoxy,propoxy, butoxy, pentyloxy, and hexyloxy groups. R^(a31) is preferably aC₁ to C₄ alkoxy group, more preferably a methoxy group or an ethoxygroup, and still more preferably a methoxy group.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the acyloxy group include acetyloxy, propionyloxy andbutyryloxy groups.

ma is preferably 0, 1 or 2, more preferably 0 or 1, still morepreferably 0.

Examples of a monomer from which the structural unit (a2-0) is derivedinclude monomers described in JP2010-204634A.

The structural unit (a2-0) having a phenolic hydroxy group is preferablya structural unit represented below.

Among these, a structural unit represented by formula (a2-0-1) andformula (a2-0-2) are preferred.

The resin (A) which has the structural units (a2-0) having a phenolichydroxy group can be produced, for example, by polymerizing a monomerwhere its phenolic hydroxy group has been protected with a suitableprotecting group, followed by deprotection. The deprotection is carriedin such a manner that an acid-labile group in the structural unit (a1)is significantly impaired. Examples of the protecting group for aphenolic hydroxy group include an acetyl group.

When the resin (A) has the structural unit (a2-0) having the phenolichydroxy group, the proportion thereof is preferably 5% by mole to 95% bymole, more preferably 10% by mole to 80% by mole, and still morepreferably 15% by mole to 80% by mole, with respect to the totalstructural units (100% by mole) constituting the resin (A).

Examples of the structural unit (a2) having an alcoholic hydroxy groupinclude the structural unit represented by formula (a2-1) (which issometimes referred to as “structural unit (a2-1)”).

In the formula (a2-1), L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—,

k2 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a14) represents a hydrogen atom or a methyl group,

R^(a15) and R^(a16) each independently represent a hydrogen atom, amethyl group or a hydroxy group, and

o1 represents an integer of 0 to 10.

In the formula (a2-1), L^(a3) is preferably —O—, —O—(CH₂)_(f1)—CO—O—,here f1 represents an integer of 1 to 4, and more preferably —O—.

R^(a14) is preferably a methyl group.

R^(a15) is preferably a hydrogen atom.

R^(a16) is preferably a hydrogen atom or a hydroxy group.

o1 is preferably an integer of 0 to 3, and more preferably an integer of0 or 1.

Examples of the monomer from which the structural unit (a2-1) is derivedinclude monomers described in JP 2010-204646A. Among these, thestructural units (a2-1) are preferably structural units represented byformula (a2-1-1) to formula (a2-1-6), more preferably structural unitsrepresented by formula (a2-1-1) to formula (a2-1-4), and still morepreferably structural units represented by formula (a2-1-1) and formula(a2-1-3).

When the resin (A) has the structural unit (a2-1) having an alcoholichydroxy group, the proportion thereof is generally 1% by mole to 45% bymole, preferably 1% by mole to 40% by mole, more preferably 1% by moleto 35% by mole, and still more preferably 2% by mole to 20% by mole,with respect to the total structural units (100% by mole) constitutingthe resin (A).

<Structural Unit (a3)>

The lactone ring included in the structural unit (a3) may be amonocyclic ring such as β-propiolactone, γ-butyrolactone,δ-valerolactone, or a condensed ring of monocyclic lactone ring withanother ring. Examples of the lactone ring preferably includeγ-butyrolactone, amadantane lactone, or bridged ring withγ-butyrolactone.

Examples of the structural unit (a3) include structural unitsrepresented by any of formula (a3-1), formula (a3-2), formula (a3-3) andformula (a3-4). These structural units may be used as a single unit oras a combination of two or more units.

In each formula, L⁴ represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3represents an integer of 1 to 7, * represents a binding site to acarbonyl group,

R^(a18) represents a hydrogen atom or a methyl group,

R^(a21) in each occurrence represents a C₁ to C₄ aliphatic hydrocarbongroup, and

p1 represents an integer of 0 to 5,

L^(a5) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents an integerof 1 to 7, * represents a binding site to a carbonyl group,

R^(a19) represents a hydrogen atom or a methyl group,

R^(a22) in each occurrence represents a carboxy group, a cyano group ora C₁ to C₄ aliphatic hydrocarbon group,

q1 represents an integer of 0 to 3,

L^(ab6) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents aninteger of 1 to 7, * represents a binding site to a carbonyl group,

R^(a20) represents a hydrogen atom or a methyl group,

R^(a23) in each occurrence represents a carboxy group, a cyano group ora C₁ to C₄ aliphatic hydrocarbon group, and

r1 represents an integer of 0 to 3,

R^(a24) represents a hydrogen atom, a halogen atom or a C₁ to C₆ alkylgroup that may have a halogen atom,

L^(a7) represents a single bond, *-L^(a8)-O—, ^(*)-L^(a8)-CO—O—,*-L^(a8)-CO—O-L^(a9)-CO—O—, or *-L^(a8)-O—CO-L^(a9)-O—; * represents abinding site to a carbonyl group, and

L^(a8) and L^(a9) each independently represent a C₁ to C₆ alkanediylgroup.

Examples of the aliphatic hydrocarbon group for R^(a21), R^(a2) andR^(a23) include an alkyl group such as methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl and tert-butyl groups.

Examples of the halogen atom for R^(a24) include fluorine, chlorine,bromine and iodine atoms;

Examples of the alkyl group for R^(a24) include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups.The alkyl group is preferably a C₁ to C₄ alkyl group, more preferably amethyl group or an ethyl group.

Examples of the alkyl group having a halogen atom of R^(a24) includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl andtriiodomethyl groups.

Examples of the alkanediyl group for L^(a8) and L^(a9) includemethylene, ethylene, propane-1,3-diyl, propane-1,2-diyl,butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl, pentane-1,4-diyl and2-methylbutane-1,4-diyl groups.

In the formulae (a3-1) to (a3-3), L^(a4) to L^(a6) is independentlypreferably —O—, *—O—(CH₂)_(k3′)—CO—O—, here k3′ represents an integer of1 to 4, more preferably —O— or *—O—CH₂—CO—O—, and still more preferably*—O—.

R^(a18) to R^(a21) is preferably a methyl group.

R^(a22) and R^(a23) are each independently preferably a carboxy group, acyano group or a methyl group.

p1, q1 and r1 are independently preferably an integer of 0 to 2, andmore preferably 0 or 1.

In the formula (a3-4), R^(a24) is preferably a hydrogen atom or a C₁ toC₄ alkyl group, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

L^(a7) is preferably a single bond or *-L^(a8)-CO—O—, and morepreferably a single bond, —CH₂—CO—O— or —C₂H₄—CO—O—.

Examples of the monomer from which the structural unit (a3) is derivedinclude monomers described in JP 2010-204646A, monomers described inJP2000-122294A and monomers described in JP2012-41274A. The structuralunits (a3) are preferably structural units represented by formula(a3-1-1) to formula (a3-1-4), formula (a3-2-1) to formula (a3-2-4),formula (a3-3-1) to formula (a3-3-4), formula (a3-4-1) to formula(a3-4-12), more preferably structural units represented by formula(a3-1-1), formula (a3-1-2), formula (a3-2-3), formula (a3-2-4), formula(a3-4-1) to formula (a3-4-12), still more preferably structural unitsrepresented by formula (a3-4-1) to formula (a3-4-12), further stillpreferably formula (a3-4-1) to formula (a3-4-6) below.

Examples of the structural unit (a3) include those represented by theformula (a3-4-1) to the formula (a3-4-12) in which a methyl groupcorresponding to R^(a24) has been replaced by a hydrogen atom.

When the resin (A) has the structural units (a3), the total proportionthereof is preferably 5% by mole to 70% by mole, more preferably 10% bymole to 65% by mole, still more preferably 10% by mole to 60% by mole,with respect to the total structural units (100% by mole) constitutingthe resin (A).

The proportion each of the formula (a3-1), the formula (a3-2), theformula (a3-3) and the formula (a3-4) is preferably 5% by mole to 60% bymole, more preferably 5% by mole to 50% by mole, still more preferably10% by mole to 50% by mole, with respect to the total structural units(100% by mole) constituting the resin (A).

<Other Structural Unit (t)>

The resin (A) may further have a structural unit other than thestructural unit (a1) and the structural unit (s) described above (whichis structural unit (t)). Examples of the structural unit (t) include thestructural unit (a4), the structural unit (a5) described above otherthan the structural unit (a2) and the structural unit (a3).

When the resin (A) further has the structural unit (a4), the proportionthereof is preferably 1 to 20% by mole, more preferably 2 to 15% bymole, and still more preferably 3 to 10% by mole, with respect to thetotal structural units (100% by mole) of the resin (A).

When the resin (A) further has the structural unit (a5), the proportionthereof is preferably 1 to 30% by mole, more preferably 2 to 20% bymole, and still more preferably 3 to 15% by mole, with respect to thetotal structural units (100% by mole) of the resin (A).

The resin (A) is preferably a resin having the structural unit (a1) andthe structural unit (s), that is, a copolymer of the monomer (a1) andthe monomer (s). In this copolymer, the structural unit (a1) ispreferably at least one of the structural unit (a1-0), the structuralunit (a1-1), the structural unit (a1-2) (preferably the structural unithaving a cyclohexyl group or a cyclopentyl group) and the structuralunit (a1-5), and more preferably is the structural unit (a1-1) or thestructural unit (a1-2) (preferably the structural unit having acyclohexyl group or a cyclopentyl group).

The structural unit (s) is preferably at least one of the structuralunit (a2) and the structural unit (a3). The structural unit (a2) ispreferably the structural unit represented by the formula (a2-1). Thestructural unit (a3) is preferably the structural unit having at leastone of a γ-butyrolactone ring, a bridged ring including aγ-butyrolactone ring or an adamantane lactone ring.

The proportion of the structural unit derived from the monomer having anadamantyl group (in particular, the structural unit (a1-1)) in the resin(A) is preferably 15% by mole or more with respect to the structuralunits (a1). As the mole ratio of the structural unit derived from themonomer having an adamantyl group increases within this range, the dryetching resistance of the resulting resist improves.

The resin (A) can be produced by a known polymerization method, forexample, radical polymerization method, using one or more species ofmonomers inducing the structural units as described above. Theproportion of the structural unit in the resin (A) can be adjusted bychanging the amount of a monomer used in polymerization.

The weight average molecular weight of the resin (A) is preferably 2,000or more (more preferably 2,500 or more, and still more preferably 3,000or more), and 50,000 or less (more preferably 30,000 or less, and stillmore preferably 15,000 or less).

The proportion of the resin (X) is preferably 1 to 60 parts by mass,more preferably 1 to 50 parts by mass, and still more preferably 1 to 40parts by mass, in particular preferably 2 to 30 parts by mass, withrespect to the resin (A) (100 parts by mass).

The total proportion of the resin (A) and the resin (X) is preferably80% by mass to 99% by mass, more preferably 90% by mass to 99% by mass,with respect to the total amount of solid components of the resistcomposition.

The proportion of the solid components in the resist composition andthat of the resins in the solid components can be measured with a knownanalytical method such as liquid chromatography and gas chromatography.

<Acid Generator (B)>

The acid generator (B) may be an ionic acid generator or a non-ionicacid generator. The acid generator (B) may be used any an ionic acidgenerator and a non-ionic acid generator. Examples of the nonioniccompounds for the acid generator include organic halogenated compounds;sulfonate esters, e.g. 2-nitrobenzylester, aromatic sulfonates,oximesulfonate, N-sulfonyloxyimide, sulfonyloxyketone, anddiazonaphtoquione 4-sulfonate; sulfones, e.g., disulfone, ketosulfone,and sulfonium diazomethane. The ionic compounds for the acid generatorinclude onium salts having an onium cation, e.g., diazonium salts,phosphonium salts, sulfonium salts and iodonium salts. Examples of theanions of onium salt include a sulfonic acid anion, a sulfonylimideanion, sulfonylmethide anion.

As the acid generator, the compounds giving an acid by radiation can beused, which are mentioned in JPS63-26653A1, JPS55-164824A1,JPS62-69263A1, JPS63-146038A1, JPS63-163452A1, JPS62-153853A1,JPS63-146029A1, U.S. Pat. No. 3,779,778B1, U.S. Pat. No. 3,849,137B1,DE3914407 and EP126,712A1. The acid generator for the photoresistcomposition can be produced by the method described in theabove-mentioned documents.

In the resist composition of the disclosure, the acid generator (B) maybe used as a single salt or as a combination of two or more of salts.

The acid generator (B) is preferably a fluorine-containing compound,more preferably a salt represented by formula (B1) (which is sometimesreferred to as “acid generator (B1)”):

wherein Q¹ and Q² each respectively represent a fluorine atom or a C₁ toC₆ perfluoroalkyl group,

L^(b1) represents a C₁ to C₂₄ divalent saturated hydrocarbon group wherea methylene group may be replaced by an oxygen atom or a carbonyl groupand a hydrogen atom may be replaced by a hydroxyl group or fluorineatom, and

Y represents an optionally substituted methyl group or an optionallysubstituted C₃ to C₁₈ alicyclic hydrocarbon group, and a methylene groupcontained in the alicyclic hydrocarbon group may be replaced by anoxygen atom, a carbonyl group or a sulfonyl group, and

Z⁺ represents an organic cation.

Examples of the perfluoroalkyl group of Q¹ and Q² includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl and perfluorohexyl groups.

Q¹ and Q² independently are preferably a trifluoromethyl group or afluorine atom, and both of Q¹ and Q² are more preferably a fluorineatom.

Examples of the divalent saturated hydrocarbon group for L″ include anyof a chain or a branched alkanediyl group, a divalent saturatedmonocyclic- or a polycyclic alicyclic hydrocarbon group, and acombination thereof.

Specific examples of the chain alkanediyl group include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl,dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl,pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diylgroups.

Specific examples of the branched chain alkanediyl group includeethane-1,1-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-2,2-diyl,pentane-1,4-diyl, pentane-2,4-diyl, 2-methylpropane-1,3-diyl,2-methylpropane-1,2-diyl and 2-methylbutane-1,4-diyl groups.

Specific examples of the saturated monocyclic alicyclic hydrocarbongroup include a cycloalkanediyl group such as cyclobutan-1,3-diyl,cyclopentan-1,3-diyl, cyclohexane-1,4-diyl and cyclooctan-1,5-diylgroups.

Specific examples of the saturated polycyclic alicyclic hydrocarbongroup include norbornane-1,4-diyl, norbornane-2,5-diyl,adamantane-1,5-diyl and adamantane-2,6-diyl groups.

Examples of the divalent saturated hydrocarbon group for L^(b1) in whicha methylene group has been replaced by oxygen atom or a carbonyl groupinclude the following groups represented by formula (b1-1) to formula(b1-3):

wherein L^(b2) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L^(b3) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the carbon atoms contained in L^(b2) and L^(b3) is 22 orless in total;

L^(b4) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b5) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the carbon atoms contained in L^(b4) and L^(b5) is 22 orless in total; L^(b6) represents a single bond or a C₁ to C₂₃ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom or a hydroxy group;

L^(b7) represents a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the carbon atoms contained in L^(b6) and L^(b7) is 23 orless in total, and

* represents a binding site to Y.

In formula (b1-1) to formula (b1-3), when a methylene group has beenreplaced by an oxygen atom or a carbonyl group, the carbon atoms of thesaturated hydrocarbon group corresponds to the carbon atoms beforereplacement.

Examples of the divalent saturated hydrocarbon group are the sameexamples as the divalent saturated hydrocarbon group of L^(b1).

L^(b2) is preferably a single bond.

L^(b3) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b4) is preferably a C₁ to C₈ divalent saturated hydrocarbon groupwhere a hydrogen atom may be replaced by a fluorine atom.

L^(b5) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b6) is preferably a single bond or a C₁ to C₄ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom.

L^(b7) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and where a methylene group may be replaced byan oxygen atom or a carbonyl group.

Among these, the group represented by the formula (b1-1) or the formula(b1-3) is preferred.

Examples of the divalent group represented by the formula (b1-1) includethe following groups represented by formula (b1-4) to formula (b1-8):

wherein L^(b8) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom or a hydroxy group;

L^(b9) represents a C₁ to C₂₀ divalent saturated hydrocarbon group;

L^(b10) represents a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the carbon atoms contained in L^(b9) and L^(b19) is 20 orless in total;

L^(b11) represents a C₁ to C₂₁ divalent saturated hydrocarbon group;

L^(b12) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the carbon atoms contained in L^(b11) and L^(b12) is 21 orless in total;

L^(b13) represents a C₁ to C₁₉ divalent saturated hydrocarbon group;

L^(b14) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group;

L^(b15) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the carbon atoms contained in L^(b13), L^(b14) and L^(b15)is 19 or less in total;

L^(b16) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b17) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b18) represents a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the carbon atoms contained in L^(b16), L^(b17) and L^(b18)is 19 or less in total.

L^(b8) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b9) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b10) is preferably a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b11) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b12) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b13) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b14) is preferably a single bond or a C₁ to C₆ divalent saturatedhydrocarbon group.

L^(b15) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b16) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b17) is preferably a C₁ to C₆ divalent saturated hydrocarbon group.

L^(b18) is preferably a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₄divalent saturated hydrocarbon group.

Examples of the divalent group represented by the formula (b1-3) includethe following groups represented by formula (b1-9) to formula (b1-11):

wherein L^(b19) represents a single bond or a C₁ to C₂₃ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L^(b20) represent a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the carbon atoms contained in L^(b19) and L^(b20) is 23 orless in total;

L^(b21) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b22) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b23) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the carbon atoms contained in L^(b21), L^(b22) and L^(b23)is 21 or less in total;

L^(b24) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b25) represents a C₁ to C₂₁ divalent saturated hydrocarbon group;

L^(b26) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the carbon atoms contained in L^(b24), L^(b25) and L^(b26)is 21 or less in total.

In formula (b1-9) to formula (b1-11), when a hydrogen atom has beenreplaced by an acyloxy group, the carbon atoms of the saturatedhydrocarbon group corresponds to the number of the carbon atom, CO and Oin addition to the carbon atoms of the saturated hydrocarbon group.

Examples of the acyloxy group include acetyloxy, propionyloxy,butyryloxy, cyclohexyl carbonyloxy and adamantyl carbonyloxy groups.

Examples of the acyloxy group having a substituent include oxoadamantylcarbonyloxy, hydroxyadamantyl carbonyloxy, oxocyclohexyl carbonyloxy andhydroxycyclohexyl carbonyloxy groups.

Examples of the group represented by the formula (b1-4) include thefollowing ones.

Examples of the group represented by the formula (b1-5) include thefollowing ones.

Examples of the group represented by the formula (b1-6) include thefollowing ones.

Examples of the group represented by the formula (b1-7) include thefollowing ones.

Examples of the group represented by the formula (b1-8) include thefollowing ones.

Examples of the group represented by the formula (b1-2) include thefollowing ones.

Examples of the group represented by the formula (b1-9) include thefollowing ones.

Examples of the group represented by the formula (b1-10) include thefollowing ones.

Examples of the group represented by the formula (b1-11) include thefollowing ones.

Examples of the monovalent alicyclic hydrocarbon group for Y includegroups represented by formula (Y1) to formula (Y11).

Examples of the monovalent alicyclic hydrocarbon group for Y in which amethylene group has been replaced by an oxygen atom, a carbonyl group ora sulfonyl group include groups represented by formula (Y12) to formula(Y27).

Among these, the alicyclic hydrocarbon group is preferably any one ofgroups represented by the formula (Y1) to the formula (Y20), morepreferably any one of groups represented by the formula (Y11), (Y15),(Y16) or (Y20), and still more preferably group represented by theformula (Y11) or (Y15).

Examples of the substituent of methyl group for Y include a halogenatom, a hydroxyl group, a C₃ to C₁₆ monovalent alicyclic hydrocarbongroup, a C₆ to C₁₈ monovalent aromatic hydrocarbon group, a glycidyloxygroup and —(CH₂)_(j2)—O—CO—R^(b1)—, in which R^(b1) represents an C₁ toC₁₆ alkyl group, a C₃ to C₁₆ monovalent alicyclic hydrocarbon group, ora C₆ to C₁₈ monovalent aromatic hydrocarbon group, and j2 represents aninteger of 0 to 4.

Examples of the substituent of the alicyclic group for Y include ahalogen atom, a hydroxyl group, a C₁ to C₁₂ alkyl group, a hydroxygroup-containing C₁ to C₁₂ alkyl group, a C₃ to C₁₆ monovalent alicyclichydrocarbon group, a C₁ to C₁₂ alkoxy group, a C₆ to C₁₈ monovalentaromatic hydrocarbon group, a C₇ to C₂₁ aralkyl group, a C₂ to C₄ acylgroup, a glycidyloxy group and —(CH₂)_(j2)—O—CO—R^(b1)—, in which R^(b1)represents an C₁ to C₁₆ alkyl group, a C₃ to C₁₆ monovalent alicyclichydrocarbon group, or a C₆ to C₁₈ monovalent aromatic hydrocarbon group,and j2 represents an integer of 0 to 4.

Examples of the hydroxy group-containing alkyl group includehydroxymethyl and hydroxyethyl groups

Examples of the alkoxyl group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxygroups.

Examples of the monovalent aromatic hydrocarbon group include an arylgroup such as phenyl, naphthyl, anthryl, p-methylphenyl,p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl,biphenyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

Examples of the aralkyl group include benzyl, phenethyl, phenylpropyl,naphthylmethyl and naphthylethyl groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of Y include the groups below. * represents a binding site toL^(b1).

When Y is methyl group and L^(b1) is a liner or branched C₁ to C₁₇divalent saturated hydrocarbon group, a methylene group which iscontained in the divalent saturated hydrocarbon group and is positionedat a bonding site of Y preferably replaces with —O— or —CO—.

Y is preferably a C₃ to C₁₈ monovalent alicyclic hydrocarbon group whichmay have a substituent, more preferably an adamantyl group which mayhave a substituent and one or more methylene group contained in theadamantyl group may be replaced with an oxygen atom, a carbonyl group ora sulfonyl group, and still more preferably an adamantyl group, ahydroxyadamantyl group or an oxoadamantyl group.

The sulfonic acid anion in the salt represented by the formula (B1) ispreferably an anions represented by formula (B1-A-1) to formula(B1-A-33), and more preferably an anions represented by formula (B1-A-1)to formula (B1-A-4), formula (B1-A-9), formula (B1-A-10), formula(B1-A-24) to formula (B1-A-33), below.

In formula (B1-A-1) to formula (B1-A-33), R¹² to R¹⁷ each independentlyrepresent a C₁ to C₄ alkyl group, and preferably a methyl group or anethyl group, R¹⁸ represent a C₁ to C₁₂ aliphatic hydrocarbon group,preferably a C₁ to C₄ alkyl group, a C₅ to C₁₂ monovalent alicyclichydrocarbon group or a group formed by a combination thereof, morepreferably a methyl group, an ethyl group, a cyclohexyl group or anadamantyl group. L⁴⁴ represents a single bond or a C₁ to C₄ alkanediylgroup. Q¹ and Q² represent the same meaning as defined above.

Specific examples of the sulfonic acid anion in the salt represented bythe formula (B1) include anions mentioned in JP2010-204646A1.

Among these, preferred examples of the sulfonic acid anion for the saltrepresented by the formula (B1) include anions represented by formulae(B1a-1) to (B1a-15).

Preferred examples of the sulfonic acid anion include anions representedby the formulae (B1a-1) to (B1a-3) and (B1a-7) to (B1a-15).

Examples of the organic cation represented by Z⁺ include an organiconium cation such as an organic sulfonium cation, an organic iodoniumcation, an organic ammonium cation, a benzothiazolium cation and anorganic phosphonium cation. An organic sulfonium cation and an organiciodonium cation are preferred, and an arylsulfonium cation is morepreferred.

Z⁺ of the formula (B1) is preferably represented by any of formula(b2-1) to formula (b2-4):

wherein R^(b4), R^(b5) and R^(b6) each independently represent a C₁ toC₃₀ aliphatic hydrocarbon group, a C₃ to C₃₆ alicyclic hydrocarbon groupor a C₆ to C₃₆ aromatic hydrocarbon group, a hydrogen atom contained inthe aliphatic hydrocarbon group may be replaced by a hydroxy group, a C₁to C₁₂ alkoxy group, a C₃ to C₁₂ alicyclic hydrocarbon group or a C₆ toC₁₈ aromatic hydrocarbon group, a hydrogen atom contained in thealicyclic hydrocarbon group may be replaced by a halogen atom, a C₁ toC₁₈ aliphatic hydrocarbon group, a C₂ to C₄ acyl group or a glycidyloxygroup, a hydrogen atom contained in the aromatic hydrocarbon group maybe replaced by a halogen atom, a hydroxy group or a C₁ to C₁₂ alkoxygroup, or R^(b4) and R^(b5) may be bonded together with a sulfur atombonded thereto to form a sulfur-containing ring, a methylene groupcontained in the ring may be replaced by an oxygen atom, a —SO— or acarbonyl group;

R^(b7) and R^(b8) in each occurrence independently represent a hydroxygroup, a C₁ to C₁₂ aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxygroup,

m2 and n2 each independently represent an integer of 0 to 5;

R^(b9) and R^(b10) each independently represent a C₁ to C₃₆ aliphatichydrocarbon group or a C₃ to C₃₆ alicyclic hydrocarbon group, or R^(b9)and R^(b10) may be bonded together with a sulfur atom bonded thereto toform a sulfur-containing ring, and a methylene group contained in thering may be replaced by an oxygen atom, a —SO— or a carbonyl group;

R¹¹ represents a hydrogen atom, a C₁ to C₃₆ aliphatic hydrocarbon group,a C₃ to C₃₆ alicyclic hydrocarbon group or a C₆ to C₁₈ aromatichydrocarbon group;

R^(b12) represents a C₁ to C₁₂ aliphatic hydrocarbon group, a C₃ to C₁₈alicyclic hydrocarbon group and a C₆ to C₁₈ aromatic hydrocarbon group,a hydrogen atom contained in the aliphatic hydrocarbon group may bereplaced by a C₆ to C₁₈ aromatic hydrocarbon group, and a hydrogen atomcontained in the aromatic hydrocarbon group may be replaced by a C₁ toC₁₂ alkoxy group or a C₁ to C₁₂ alkyl carbonyloxy group;

R^(b11) and R^(b12) may be bonded together with —CH—CO— bonded theretoto form a ring, and a methylene group contained in the ring may bereplaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) in eachoccurrence independently represent a hydroxy group, a C₁ to C₁₂aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxy group;

L^(b31) represents —S— or —O—;

o2, p2, s2 and t2 independently represent an integer of 0 to 5;

q2 or r2 independently represent an integer of 0 to 4; and

u2 represents an integer of 0 or 1.

Examples of the aliphatic group include an alkyl group such as methyl,ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl,n-hexyl, n-octyl and 2-ethylhexyl groups. Among these, the aliphatichydrocarbon group for R^(b9) to R^(b12) is preferably a C₁ to C₁₂aliphatic hydrocarbon group.

Examples of the alicyclic hydrocarbon group include monocyclic groupssuch as a cycloalkyl group, i.e., cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl groups; and polycyclicgroups such as decahydronaphtyl, adamantyl and norbornyl groups as wellas the following groups. * represents a binding site.

Among these, the alicyclic hydrocarbon group for R^(b9) to R^(b12) ispreferably a C₃ to C₁₈ alicyclic hydrocarbon group, and more preferablya C₄ to C₁₂ alicyclic hydrocarbon group.

Examples of the alicyclic hydrocarbon group where a hydrogen atom may bereplaced by an aliphatic hydrocarbon group include methylcyclohexyl,dimethylcyclohexyl, 2-alkyladamantane-2-yl, methylnorbornyl andisobornyl groups. In the alicyclic hydrocarbon group where a hydrogenatom may be replaced by an aliphatic hydrocarbon group, the carbon atomsof the alicyclic hydrocarbon group and the aliphatic hydrocarbon groupis preferably 20 or less in total.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, tolyl, xylyl, cumenyl, mesityl, p-ethylphenyl,p-tert-butylphenyl, p-cyclohexylphenyl, p-adamantylphenyl, biphenyl,naphthyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

When the aromatic hydrocarbon has an aliphatic hydrocarbon group or analicyclic hydrocarbon group, a C₁ to C₁₈ aliphatic hydrocarbon group ora C₃ to C₁₈ alicyclic hydrocarbon group is preferred.

Examples of the aromatic hydrocarbon group where a hydrogen atom may bereplaced by an alkoxy group include a p-methoxyphenyl group.

Examples of the aliphatic hydrocarbon group where a hydrogen atom may bereplaced by an aromatic hydrocarbon group include an aralkyl group suchas benzyl, phenethyl phenylpropyl, trityl, naphthylmethyl andnaphthylethyl groups.

Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxygroups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkylcarbonyloxy group include methylcarbonyloxy,ethylcarbonyloxy, n-propylcarbonyloxy, isopropylcarbonyloxy,n-butylcarbonyloxy, sec-butylcarbonyloxy, tert-butyl carbonyloxy,pentylcarbonyloxy, hexylcarbonyloxy, octylcarbonyloxy and2-ethylhexylcarobonyloxy groups.

The sulfur atom-containing ring which is formed by R^(b4) and R^(b5) maybe a monocyclic or polycyclic group, which may be an aromatic ornon-aromatic group, and which may be a saturated or unsaturated group.The ring is preferably a ring having 3 to 18 carbon atoms, and morepreferably a ring having 4 to 18 carbon atoms. Examples of the sulfuratom-containing ring include a 3- to 12-membered ring, preferably a 3-to 7-membered ring, examples thereof include the following rings.

The sulfur atom-containing ring which is formed by R^(b9) and R^(b10)may be any of monocyclic, polycyclic, aromatic, non-aromatic, saturatedand unsaturated rings. The ring may be a 3- to 12-membered ring,preferably a 3- to 7-membered ring. Examples of the ring includethiolane-1-ium ring (tetrahydrothiophenium ring), thian-1-ium ring and1,4-oxathian-4-ium ring.

Examples of the ring formed by R^(b11) and R^(b12) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring. Examples of the ring include oxocycloheptanering, oxocyclohexane ring, oxonorbornane ring and oxoadamantane ring.

Among the cations represented by the formula (b2-1) to the formula(b2-4), the cation represented by the formula (b2-1) is preferred.

Examples of the cation represented by the formula (b2-1) include thefollowing ones.

Examples of the cation represented by the formula (b2-2) include thefollowing ones.

Examples of the cation represented by the formula (b2-3) include thefollowing ones.

Examples of the cation represented by the formula (b2-4) include thefollowing ones.

The acid generator (B1) is generally a compound which consists of theabove sulfonate anion with an organic cation. The above sulfonic acidanion and the organic cation may optionally be combined. Preferredcombination is a combination of any of the anion represented by theformula (B1a-1) to the formula (B1a-3), the formula (B1a-7) to theformula (B1a-15) and the cation represented by the formula (b2-1) or theformula (b2-3).

Preferred acid generators (B1) are represented by formula (B1-1) toformula (B1-30). Among these, formulae (B1-1), (B1-2), (B1-3), (B1-5),(B1-6), (B1-7), (B1-11), (B1-12), (B1-13), (B1-14), (B1-17), (B1-20),(B1-21), (B1-23), (B1-24), (B1-25), (B1-26) and (B1-29) which containarylsulfonium cation are preferred.

The proportion of the acid generator (B1) is preferably 30% by mass ormore, and 100% by mass or less, more preferably 50% by mass or more, and100% by mass or less, and still more preferably substantially 100% byweight with respect to 100% by mass of total acid generator (B).

In the resist composition of the disclosure, the proportion of the acidgenerator (B) is preferably 1 parts by mass or more and more preferably3 parts by mass or more, and preferably 30 parts by mass or less andmore preferably 25 parts by mass or less with respect to 100 parts bymass of the resin (A1).

<Solvent (E)>

The proportion of a solvent (E) is generally 90% by mass or more,preferably 92% by mass or more, and more preferably 94% by mass or more,and also preferably 99% by mass or less, and more preferably 99.9% bymass or less. The proportion of the solvent (E) can be measured with aknown analytical method such as liquid chromatography and gaschromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate andpropyleneglycolmonomethylether acetate; glycol ethers such aspropyleneglycolmonomethylether; esters such as ethyl lactate, butylacetate, amyl acetate and ethyl pyruvate; ketones such as acetone,methyl isobutyl ketone, 2-heptanone and cyclohexanone; and cyclic esterssuch as γ-butyrolactone. These solvents may be used as a single solventor as a mixture of two or more solvents.

<Quencher (C)>

The resist composition of the disclosure may further contain a quenchersuch as a basic nitrogen-containing organic compound and a salt whichgenerates an acid weaker in acidity than an acid generated from the acidgenerator.

Examples of the quencher include a basic nitrogen-containing organiccompound and a salt which generates an acid weaker in acidity than anacid generated from the acid generator (B).

<Basic Nitrogen-Containing Organic Compound>

Examples of the basic nitrogen-containing organic compound include anamine and ammonium salts.

Examples of the amine include an aliphatic amine and an aromatic amine.Examples of the aliphatic amine include a primary amine, secondary amineand tertiary amine. Specific examples of the amine include1-naphtylamine, 2-naphtylamine, aniline, diisopropylaniline, 2-, 3- or4-methylaniline, 4-nitroaniline, N-methylaniline, N,N-dimethylaniline,diphenylamine, hexylamine, heptylamine, octylamine, nonylamine,decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine,dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine,tripropylamine, tributylamine, tripentylamine, trihexylamine,triheptylamine, trioctylamine, trinonylamine, tridecylamine,methyldibutylamine, methyldipentylamine, methyldihexylamine,methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine,methyldinonylamine, methyldidecylamine, ethyldibutylamine,ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine,ethyldioctylamine, ethyldinonylamine, ethyldidecylamine,dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine,triisopropanolamine, ethylene diamine, tetramethylene diamine,hexamethylene diamine, 4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane,di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine and bipyridine. Among these,diisopropylaniline is preferred, particularly 2,6-diisopropylaniline ismore preferred.

Specific examples of the ammonium salt include tetramethylammoniumhydroxide, tetraisopropylammonium hydroxide, tetrabutylammoniumhydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethyl ammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate and choline.

<Weak Acid Salt>

The salt generating an acid which is lower in acidity than an acidgenerated from the acid generator (B) is sometimes referred to as “weakacid salt”. The “acidity” can be represented by acid dissociationconstant, pKa, of an acid generated from a weak acid salt. Examples ofthe weak acid salt include a salt generating an acid of pKa representsgenerally more than −3, preferably −1 to 7, and more preferably 0 to 5.

Specific examples of the weak acid salt include the following salts, thesalt of formula (D), and salts as disclosed in JP2012-229206A1,JP2012-6908A1, JP2012-72109A1, JP2011-39502A1 and JP2011-191745A1.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlyrepresent a C₁ to C₁₂ hydrocarbon group, a C₁ to C₆ alkoxyl group, a C₂to C₇ acyl group, a C₂ to C₇ acyloxy group, a C₂ to C₇ alkoxycarbonylgroup, a nitro group or a halogen atom;

m′ and n′ each independently represent an integer of 0 to 4.

Examples of the hydrocarbon group of R^(D1) and R^(D2) include any of analiphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group and a combination thereof.

Examples of the aliphatic hydrocarbon group include an alkyl group suchas methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl,pentyl, hexyl and nonyl groups.

The alicyclic hydrocarbon group is any one of monocyclic or polycyclichydrocarbon group, and saturated or unsaturated hydrocarbon group.Examples thereof include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl and cyclododecyl groups;adamantyl and norbornyl groups.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, 1-naphthyl, 2-naphthyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl,4-butylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl,anthryl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the combination thereof include an alkyl-cycloalkyl, acycloalkyl-alkyl, aralkyl (e.g., phenylmethyl, 1-phenylethyl,2-phenylethyl, 1-phenyl-1-propyl, 1-phenyl-2-propyl, 2-phenyl-2-propyl,3-phenyl-1-propyl, 4-phenyl-1-butyl, 5-phenyl-1-pentyl and6-phenyl-1-hexyl groups) groups.

Examples of the alkoxyl group include methoxy and ethoxy groups.

Examples of the acyl group include acetyl, propanonyl, benzoyl andcyclohexanecarbonyl groups.

Examples of the acyloxy group include a group in which oxy group (—O—)bonds to an acyl group.

Examples of the alkoxycarbonyl group include a group in which thecarbonyl group (—CO—) bonds to the alkoxy group.

Example of the halogen atom is a chlorine atom, a fluorine atom andbromine atom.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlypreferably represent a C₁ to C₈ alkyl group, a C₃ to C₁₀ cycloalkylgroup, a C₁ to C₆ alkoxyl group, a C₂ to C₄ acyl group, a C₂ to C₄acyloxy group, a C₂ to C₄ alkoxycarbonyl group, a nitro group or ahalogen atom.

m′ and n′ independently preferably represent an integer of 0 to 3, morepreferably an integer of 0 to 2, and more preferably 0.

Specific examples of the salt of the formula (D) include compoundsbelow.

The salt of the formula (D) can be produced by a method described in“Tetrahedron Vol. 45, No. 19, p6281-6296”. Also, commercially availablecompounds can be used as the salt of the formula (D).

In the resist composition of the disclosure, the proportion of thequencher is preferably 0.01% by mass to 5% by mass, more preferably0.01% by mass to 4% by mass, and still more preferably 0.01% by mass to3% by mass with respect to total solid components of the resistcomposition.

<Other Ingredient>

The resist composition can also contain other ingredient (which issometimes referred to as “other ingredient (F)”). Examples of the otheringredient (F) include various additives such as sensitizers,dissolution inhibitors, surfactants, stabilizers, and dyes, as needed.

<Preparing the Resist Composition>

The present resist composition can be prepared by mixing the resins (X)and (A), the acid generator (B), the quencher (C), the solvent (E) andthe other ingredient (F), as needed. There is no particular limitationon the order of mixing. The mixing may be performed in an arbitraryorder. The temperature of mixing may be adjusted to an appropriatetemperature within the range of 10 to 40° C., depending on the kinds ofthe resin and solubility in the solvent (E) of the resin. The time ofmixing may be adjusted to an appropriate time within the range of 0.5 to24 hours, depending on the mixing temperature. There is no particularlimitation to the tool for mixing. An agitation mixing may be used.

After mixing the above ingredients, the present resist compositions canbe prepared by filtering the mixture through a filter having about 0.003to 0.2 μm pore diameter.

<Method for Producing Resist Pattern>

The method for producing a resist pattern of the disclosure includes thesteps of:

(1) applying the resist composition of the disclosure onto a substrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

Applying the resist composition onto the substrate can generally becarried out through the use of a resist application device, such as aspin coater known in the field of semiconductor microfabricationtechnique. Examples of the substrate include inorganic substrates suchas silicon wafer. The substrate may be washed, and an organicantireflection film may be formed on the substrate by use of acommercially available antireflection composition, before theapplication of the resist composition.

The solvent evaporates from the resist composition and a compositionlayer with the solvent removed is formed. Drying the applied compositionlayer, for example, can be carried out using a heating device such as ahotplate (so-called “prebake”), a decompression device, or a combinationthereof. The temperature is preferably within the range of 50 to 200° C.The time for heating is preferably 10 to 180 seconds. The pressure ispreferably within the range of 1 to 1.0×10⁵ Pa.

The obtained composition layer is generally exposed using an exposureapparatus or a liquid immersion exposure apparatus. The exposure isgenerally carried out using with various types of exposure light source,such as irradiation with ultraviolet lasers, i.e., KrF excimer laser(wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm), F₂ excimerlaser (wavelength: 157 nm), irradiation with harmonic laser light offar-ultraviolet or vacuum ultra violet wavelength-converted laser lightfrom a solid-state laser source (YAG or semiconductor laser or thelike), or irradiation with electron beam or EUV or the like. In thespecification, such exposure to radiation is sometimes referred to becollectively called as exposure. The exposure is generally carried outthrough a mask that corresponds to the desired pattern. When electronbeam is used as the exposure light source, direct writing without usinga mask can be carried out.

After exposure, the composition layer is subjected to a heat treatment(so-called “post-exposure bake”) to promote the deprotection reaction.The heat treatment can be carried out using a heating device such as ahotplate. The heating temperature is generally in the range of 50 to200° C., preferably in the range of 70 to 150° C.

The developing of the baked composition film is usually carried out witha developer using a development apparatus. Developing can be conductedin the manner of dipping method, paddle method, spray method and dynamicdispensing method. Temperature for developing is generally 5 to 60° C.The time for developing is preferably 5 to 300 seconds.

The photoresist pattern obtained from the photoresist composition may bea positive one or a negative one by selecting suitable developer.

The development for obtaining a positive photoresist pattern is usuallycarried out with an alkaline developer. The alkaline developer to beused may be any one of various alkaline aqueous solution used in theart. Generally, an aqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. The surfactant may be contained in thealkaline developer.

After development, the resist pattern formed is preferably washed withultrapure water, and the residual water remained on the resist film oron the substrate is preferably removed therefrom.

The development for obtaining a negative photoresist pattern is usuallycarried out with a developer containing an organic solvent. The organicsolvent to be used may be any one of various organic solvents used inthe art, examples of which include ketone solvents such as 2-hexanone,2-heptanone; glycol ether ester solvents such aspropyleneglycolmonomethylether acetate; ester solvents such as the butylacetate; glycol ether solvents such as thepropyleneglycolmonomethylether; amide solvents such asN,N-dimethylacetamide; aromatic hydrocarbon solvents such as anisole.

In the developer containing an organic solvent, the amount of organicsolvents is preferably 90% by mass to 100% by mass, more preferably 95%by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of organic solvents.

Among these, the developer containing an organic solvent preferablycontains butyl acetate and/or 2-heptanone. In the developer containingan organic solvent, the total amount of butyl acetate and 2-heptanone ispreferably 50% by mass to 100% by mass of the developer, more preferably90% by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of butyl acetate and/or 2-heptanone.

Developers containing an organic solvent may contain a surfactant. Also,the developer containing an organic solvent may include a little water.

The developing with a developer containing an organic solvent can befinished by replacing the developer by another solvent.

After development, the photoresist pattern formed is preferably washedwith a rinse agent. Such rinse agent is not unlimited provided that itdoes not detract a photoresist pattern. Examples of the agent includesolvents which contain organic solvents other than the above-mentioneddevelopers, such as alcohol agents or ester agents.

After washing, the residual rinse agent remained on the substrate orphotoresist film is preferably removed therefrom.

<Application>

The resist composition of the disclosure is useful for excimer laserlithography such as ArF, KrF, electron beam (EB) exposure lithography orextreme-ultraviolet (EUV) exposure lithography, and is more useful forArF excimer laser exposure lithography.

The resist composition of the disclosure can be used in semiconductormicrofabrication.

EXAMPLES

The disclosure will be described more specifically by way of examples,which are not construed to limit the scope of the disclosure.

All percentages and parts expressing the content or amounts used in theExamples and Comparative Examples are based on mass, unless otherwisespecified.

The weight average molecular weight is a value determined by gelpermeation chromatography.

Column: TSK gel Multipore HXL-M x 3+guardcolumn (Tosoh Co. Ltd.)

Eluant: tetrahydrofuran

Flow rate: 1.0 mL/min

Detecting device: RI detector

Column temperature: 40° C.

Injection amount: 100 μL

Standard material for calculating molecular weight: standard polystyrene(Tosoh Co. ltd.)

Structures of compounds were determined by mass spectrometry (LiquidChromatography: 1100 Type, manufactured by AGILENT TECHNOLOGIES LTD.,Mass Spectrometry: LC/MSD Type, manufactured by AGILENT TECHNOLOGIESLTD.). The value of the peak in the mass spectrometry is referred to as“MASS”.

Example 1 Synthesis of the Compound Represented by Formula (I-1)

Into a reactor, 10 parts of the compound represented by the formula(I-1-b), 50 parts of chloroform, 4.48 parts of pyridine, 12.27 parts ofthe compound represented by the formula (I-1-a) and 9.94 parts of thecompound represented by the formula (I-1-c) were charged, then, stirredat 23° C. for 4 hours. To the obtained mixture, 90 parts of n-heptanewas added. Then, 38 parts of 5% hydrochloric acid was added to thereaction mixture, and stirred at 23° C. for 30 minutes. The mixture wasleft still, followed by separating an organic layer. The washing stepwas conducted twice. To the obtained organic layer, 45 parts ofion-exchanged water was added and stirred at 23° C. for 30 minutes, andleft still, followed by separating an organic layer to wash with water.To the obtained organic layer, 16 parts of the saturated aqueous sodiumhydrogen carbonate solution was added and stirred at 23° C. for 30minutes, and left still, followed by separating an organic layer to washwith water. To the obtained organic layer, 45 parts of ion-exchangedwater was added and stirred at 23° C. for 30 minutes, and left still,followed by separating an organic layer to wash with water. The washingstep was conducted five times. The washed organic layer was concentratedand purified with column chromatography [silica gel 60N spherical shape,neutral, 100-210 μm, solvent: ethyl acetate, manufactured by Kanto Chem.Ltd.] to obtain 4.09 parts of the compound represented by formula(I-1-d).

Into a reactor, 4.08 parts of the compound represented by the formula(I-1-d), 20 parts of tetrahydrofuran and 2.13 parts ofdimethylaminopyridine were charged, then, stirred at 23° C. for 30minutes. To the obtained mixture, 3.46 parts of the compound representedby the formula (I-1-e) was added, and stirred at 23° C. for one hour.Then, 62 parts of n-heptane was added to the mixture, and stirred at 23°C. for 2 hours. To the obtained reaction mixture, 7.5 parts of 5%hydrochloric acid was added, stirred at 23° C. for 30 minutes, and leftstill, followed by separating an organic layer. The washing step wasconducted twice. To the obtained organic layer, 7 parts of ion-exchangedwater was added and stirred at 23° C. for 30 minutes, and left still,followed by separating an organic layer to wash with water. The washingstep was conducted five times. The washed organic layer was concentratedand purified with column chromatography [silica gel 60N spherical shape,neutral, 100-210 μm, solvent: ethyl acetate, manufactured by Kanto Chem.Ltd.] to obtain 3.68 parts of the compound represented by formula (I-1).

MS (mass spectrography): 486.2 (molecular ion peak)

Example 2 Synthesis of the Compound Represented by Formula (I-9)

Into a reactor, 15 parts of the compound represented by the formula(I-9-a), 75 parts of tetrahydrofuran and 6.54 parts ofdimethylaminopyridine were charged, then, stirred at 23° C. for 30minutes. To the obtained mixture, 10.64 parts of the compoundrepresented by the formula (I-9-b) was added, then, stirred at 23° C.for one hour. 220 parts of n-heptane was added to the reaction mixture,and stirred at 23° C. for 2 hours. To the obtained mixture, 23 parts of5% hydrochloric acid was added, and stirred at 23° C. for 30 minutes.The mixture was left still, followed by separating an organic layer. Thewashing step was conducted twice. To the obtained organic layer, 22parts of ion-exchanged water was added and stirred at 23° C. for 30minutes, and left still, followed by separating an organic layer to washwith water. The washing step was conducted four times. The washedorganic layer was concentrated and purified with column chromatography[silica gel 60N spherical shape, neutral, 100-210 pm, solvent: ethylacetate, manufactured by Kanto Chem. Ltd.] to obtain 23.50 parts of thecompound represented by formula (I-9).

MS (mass spectrography): 498.2 (molecular ion peak)

Example 3 Synthesis of the Compound Represented by Formula (I-2)

Into a reactor, 4.08 parts of the compound represented by the formula(I-1-d), 20 parts of tetrahydrofuran and 2.13 parts ofdimethylaminopyridine were charged, then, stirred at 23° C. for 30minutes. To the obtained mixture, 2.55 parts of the compound representedby the formula (I-2-e) was added, then, stirred at 23° C. for one hour.62 parts of n-heptane was added to the reaction mixture, and stirred at23° C. for 2 hours. To the obtained mixture, 7.5 parts of 5%hydrochloric acid was added, and stirred at 23° C. for 30 minutes. Themixture was left still, followed by separating an organic layer. Thewashing step was conducted twice. To the obtained organic layer, 7 partsof ion-exchanged water was added and stirred at 23° C. for 30 minutes,and left still, followed by separating an organic layer to wash withwater. The washing step was conducted three times. The washed organiclayer was concentrated and purified with column chromatography [silicagel 60N spherical shape, neutral, 100-210 μm, solvent: ethyl acetate,manufactured by Kanto Chem. Ltd.] to obtain 2.16 parts of the compoundrepresented by formula (I-2).

MS (mass spectrography): 434.1 (molecular ion peak)

Example 4 Synthesis of the Compound Represented by Formula (I-15)

Into a reactor, 4.08 parts of the compound represented by the formula(I-1-d), 20 parts of tetrahydrofuran and 2.13 parts ofdimethylaminopyridine were charged, then, stirred at 23° C. for 30minutes. To the obtained mixture, 3.70 parts of the compound representedby the formula (I-15-e) was added, then, stirred at 23° C. for one hour.62 parts of n-heptane was added to the reaction mixture, and stirred at23° C. for 2 hours. To the obtained mixture, 7.5 parts of 5%hydrochloric acid was added, and stirred at 23° C. for 30 minutes. Themixture was left still, followed by separating an organic layer. Thewashing step was conducted twice. To the obtained organic layer, 7 partsof ion-exchanged water was added and stirred at 23° C. for 30 minutes,and left still, followed by separating an organic layer to wash withwater. The washing step was conducted five times. The washed organiclayer was concentrated and purified with column chromatography [silicagel 60N spherical shape, neutral, 100-210 μm, solvent: ethyl acetate,manufactured by Kanto Chem. Ltd.] to obtain 2.74 parts of the compoundrepresented by formula (I-15).

MS (mass spectrography): 500.1 (molecular ion peak)

Synthesis Example 1 Synthesis of the Salt Represented by Formula (B1-5)

Into a reactor, 50.49 parts of a salt represented by the formula(B1-5-a) and 252.44 parts of chloroform were charged and stirred at 23°C. for 30 minutes. Then 16.27 parts of a compound represented by theformula (B1-5-b) were dropped thereinto and the obtained mixture wasstirred at 23° C. for one hour to obtain a solution containing a saltrepresented by the formula (B1-5-c). To the obtained solution, 48.80parts of a salt represented by the formula (B1-5-d) and 84.15 parts ofion-exchanged water were added and the obtained mixture was stirred at23° C. for 12 hours. From the obtained solution which had two layers, achloroform layer was collected and then 84.15 parts of ion-exchangedwater were added thereto for washing. These step were conducted fivetimes. To the washed chloroform layer, 3.88 parts of active carbon wasadded and the obtained mixture was stirred, followed by filtrating. Thecollected filtrate was concentrated, and then 125.87 parts ofacetonitrile was added thereto and the obtained mixture was stirred,followed by being concentrated. 20.62 parts of acetonitrile and 309.30parts of tert-butyl methyl ether were added to the obtained residues,followed by being stirred at 23° C. for about 30 minutes. Then asupernatant was removed therefrom, and the residues were concentrated.To the concentrated residues, 200 parts of n-heptane were added and theobtained mixture was stirred at 23° C. for about 30 minutes, followed bybeing filtrated to obtain 61.54 parts of the salt represented by theformula (B1-5).

MASS(ESI(+)Spectrum):M+375.2

MASS(ESI(−)Spectrum):M−339.1

Synthesis Example 2 Synthesis of the Salt Represented by Formula (B1-21)

The compound represented by the formula (B1-21-b) was produced accordingto a method recited in JP2008-209917A1.

Into a reactor, 30.00 parts of the compound represented by the formula(B1-21-b) and 35.50 parts of a salt represented by the formula(B1-21-a), 100 parts of chloroform and 50 parts of ion-exchanged waterwere charged and stirred at 23° C. for about 15 hours. From the obtainedsolution which had two layers, a chloroform layer was collected and then30 parts of ion-exchanged water was added thereto for washing. Thesesteps were conducted five times. Then the washed layer was concentrated,and then, 100 parts of tert-butyl methyl ether was added to the obtainedresidues and the obtained mixture was stirred at 23° C. for about 30minutes. The resulting mixture was filtrated to obtain 48.57 parts ofthe salt represented by the formula (B1-21-c).

Into a reactor, 20.00 parts of salt represented by the formula(B1-21-c), 2.84 parts of compound represented by the formula (B1-21-d)and 250 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.21 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for1 hour. The reaction mixture was concentrated, and then, 200 parts ofchloroform and 50 parts of ion-exchanged water were added to theobtained residues and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer. 50 parts ofion-exchanged water was added to the obtained organic layer, and theobtained mixture was stirred at 23° C. for 30 minutes, followed byseparating an organic layer. The washing step with water was conductedfive times. The obtained organic layer was concentrated, and then theobtained residues were dissolved in 53.51 parts of acetonitrile. Thenthe mixture was concentrated, and 113.05 parts of tert-butyl methylether was added thereto and the obtained mixture was stirred, followedby filtrating it to obtain 10.47 parts of the salt represented by theformula (B1-21).

MASS(ESI(+)Spectrum):M⁺237.1

MASS(ESI(−)Spectrum):M⁻339.1

Synthesis Example 3 Synthesis of the Salt Represented by Formula (B1-22)

Into a reactor, 11.26 parts of the salt represented by the formula(B1-21-a), 10 parts of the compound represented by the formula(B1-22-b), 50 parts of chloroform and 25 parts of ion-exchanged waterwere charged and stirred at 23° C. for about 15 hours. From the obtainedsolution which had two layers, a chloroform layer was collected and then15 parts of ion-exchanged water were added thereto for washing. Thesesteps were conducted five times. Then the washed layer was concentrated,and then 50 parts of tert-butyl methyl ether was added to the obtainedresidues, and the obtained mixture was stirred at 23° C. for about 30minutes. The resulting mixture was filtrated to obtain 11.75 parts ofthe salt represented by the formula (B1-22-c).

Into a reactor, 11.71 parts of a salt represented by the formula(B1-22-c), 1.70 parts of a compound represented by the formula (B1-21-d)and 46.84 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.12 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for30 minutes. The reaction mixture was concentrated, and then 50 parts ofchloroform and 12.50 parts of ion-exchanged water were added to theobtained residues, and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer. 12.50 parts ofion-exchanged water was added to the obtained organic layer and theobtained mixture was stirred at 23° C. for 30 minutes, followed byseparating an organic layer to wash with water. The washing step withwater was conducted eight times. Then the obtained organic layer wasconcentrated, and 50 parts of tert-butyl methyl ether were added theretoand the obtained mixture was stirred, followed by filtrating it toobtain 6.84 parts of the salt represented by the formula (B1-22).

MASS(ESI(+)Spectrum):M⁺237.1

MASS(ESI(−)Spectrum):M⁻323.0

Synthesis Examples of Resins

The monomers used for Synthesis Examples of the resins are shown below.These monomers are referred to as “monomer (X)” where “(X)” is thesymbol of the formula representing the structure of each monomer.

Synthesis Example 4 Synthesis of Resin A1

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-3) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-3) and monomer (a3-4-2)=45:14:2.5:38.5,and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in another propyleneglycolmonomethylether acetate toobtain a solution, and the solution was poured into a mixture ofmethanol and water to precipitate the resin. The obtained resin wasfiltrated. These operations were repeated twice to obtain the copolymerhaving a weight average molecular weight of about 7600 in 68% yield.This resin, which had the structural units of the following formulae,was referred to Resin A1.

Synthesis Example 5 Synthesis of Resin A2

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-1) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-1) and monomer (a3-4-2)=45:14:2.5:38.5,and propyleneglycolmonomethylether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in another propyleneglycolmonomethylether acetate toobtain a solution, and the solution was poured into a mixture ofmethanol and water to precipitate the resin. The obtained resin wasfiltrated. These operations were repeated twice to obtain the copolymerhaving a weight average molecular weight of about 7900 in 70% yield.This resin, which had the structural units of the following formulae,was referred to Resin A2.

Example 5 Synthesis of Resin X1

To monomer (I-1), propyleneglycolmonomethylether acetate was added inthe amount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was poured into methanol to precipitate the resin. Theobtained resin was filtrated to obtain the polymer having a weightaverage molecular weight of about 12000 in 68% yield. This resin, whichhad the structural units of the following formula, was referred to asResin X1.

Example 6 Synthesis of Resin X2

Monomer (I-1) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-1) and monomer (a5-1-1)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 0.7% by moleand 2.1% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thepolymer having a weight average molecular weight of about 12000 in 70%yield. This resin, which had the structural units of the followingformula, was referred to Resin X2.

Example 7 Synthesis of Resin X3

To monomer (I-9) propyleneglycolmonomethylether acetate was added in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was poured into methanol to precipitate the resin. Theobtained resin was filtrated to obtain the polymer having a weightaverage molecular weight of about 13000 in 73% yield. This resin, whichhad the structural units of the following formula, was referred to asResin X3.

Example 8 Synthesis of Resin X4

Monomer (I-9) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-9) and monomer (a5-1-1)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 0.7% by moleand 2.1% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thepolymer having a weight average molecular weight of about 12000 in 76%yield. This resin, which had the structural units of the followingformulae, was referred to Resin X4.

Example 9 Synthesis of Resin X5

To monomer (I-9) propyleneglycolmonomethylether acetate was added in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was poured into methanol to precipitate the resin. The obtainedresin was filtrated to obtain the polymer having a weight averagemolecular weight of about 8200 in 76% yield. This resin, which had thestructural units of the following formula, was referred to as Resin X5.

Example 10 Synthesis of Resin X6

Monomer (I-9) and monomer (a5-1-1) were mixed together with the moleratio of monomer (I-9) and monomer (a5-1-1)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thepolymer having a weight average molecular weight of about 7900 in 70%yield. This resin, which had the structural units of the followingformula, was referred to Resin X6.

Example 11 Synthesis of Resin X7

Monomer (I-9) and monomer (a4-0-12) were mixed together with the moleratio of monomer (I-9) and monomer (a4-0-12)=50:50, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 75°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thepolymer having a weight average molecular weight of about 8400 in 76%yield. This resin, which had the structural units of the followingformulae, was referred to Resin X7.

Example 12 Synthesis of X8

Monomer (I-9), monomer (a4-0-12) and monomer (a5-1-1) were mixedtogether with the mole ratio of monomer (I-9), (a4-0-12) and monomer(a5-1-1)=50:25:25, and propyleneglycolmonomethylether acetate was addedthereto in the amount equal to 1.5 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was poured into methanol to precipitate the resin. The obtainedresin was filtrated to obtain the polymer having a weight averagemolecular weight of about 7900 in 65% yield. This resin, which had thestructural units of the following formulae, was referred to Resin X8.

Example 13 Synthesis of Resin X9

To monomer (I-2) propyleneglycolmonomethylether acetate was added in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was poured into methanol to precipitate the resin. The obtainedresin was filtrated to obtain the polymer having a weight averagemolecular weight of about 8800 in 63% yield. This resin, which had thestructural units of the following formula, was referred to as Resin X9.

Example 14 Synthesis of Resin X10

To monomer (I-15) propyleneglycolmonomethylether acetate was added inthe amount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. Thus obtainedresin was poured into methanol to precipitate the resin. The obtainedresin was filtrated to obtain the polymer having a weight averagemolecular weight of about 7800 in 63% yield. This resin, which had thestructural units of the following formula, was referred to as Resin X10.

Synthesis Example 6 Synthesis of Resin Xx1

Monomer (IX-1) and monomer (IX-2) were mixed together with the moleratio of monomer (IX-1) and monomer (IX-2)=60:40, andpropyleneglycolmonomethylether acetate was added thereto in the amountequal to 1.5 times by mass of the total amount of monomers to obtain asolution. Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile)were added as initiators to the solution in the amounts of 1% by moleand 3% by mole respectively with respect to the total amount ofmonomers, and the resultant mixture was heated for about 5 hours at 70°C. Then, the obtained reaction mixture was poured into a large amount ofa mixture of methanol and water to precipitate a resin. The obtainedresin was filtrated. Thus obtained resin was poured into methanol toprecipitate the resin. The obtained resin was filtrated to obtain thepolymer having a weight average molecular weight of about 9200 in 68%yield. This resin, which had the structural units of the followingformulae, was referred to Resin Xx1.

Synthesis Example 7 Synthesis of Resin Xx2

To monomer (IX-1) propyleneglycolmonomethylether acetate was added inthe amount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.7% by mole and 2.1% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol andwater to precipitate a resin. The obtained resin was filtrated. Thusobtained resin was poured into methanol to precipitate the resin. Theobtained resin was filtrated to obtain the polymer having a weightaverage molecular weight of about 13000 in 89% yield. This resin, whichhad the structural units of the following formula, was referred to asResin Xx2.

(Preparing Resist Compositions)

Resist compositions were prepared by mixing and dissolving each of thecomponents shown in Table 1, and then filtrating through a fluororesinfilter having 0.2 μm pore diameter. The obtained resist compositionswere stored for 3 weeks at 30° C. Then, the properties of the resistcompositions were evaluated.

TABLE 1 Acid Weakly Acidic PB/PEB Resin Generator (B) Inner Salt (D) (°C./ Resist Comp. (parts) (parts) (parts) ° C.) Composition 1 X1/A1 =B1-21/B1-22 = D1 = 0.28 90/85 0.5/10 0.9/0.4 Composition 2 X1/A1 =B1-5/B1-22 = D1 = 0.28 90/85 0.5/10 0.4/0.4 Composition 3 X2/A1 =B1-21/B1-22 = D1 = 0.28 90/85 0.5/10 0.9/0.4 Composition 4 X3/A1 =B1-21/B1-22 = D1 = 0.28 90/85 0.5/10 0.9/0.4 Composition 5 X4/A1 =B1-21/B1-22 = D1 = 0.28 90/85 0.5/10 0.9/0.4 Composition 6 X1/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 7 X2/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 8 X3/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 9 X4/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 10 X5/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 11 X6/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 12 X7/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 13 X8/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 14 X9/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Composition 15 X10/A2 =B1-21/B1-22 = D1 = 0.28 90/85 0.4/10 0.9/0.4 Comparative Xx1/A1 =B1-21/B1-22 = D1 = 0.28 90/85 Comp. 1 0.5/10 0.9/0.4 Comparative Xx2/A1= B1-21/B1-22 = D1 = 0.28 90/85 Comp. 2 0.5/10 0.9/0.4

<Resin>

A1, A2, X1 to X10, Xx1, Xx2: Resins A1, A2, X1 to X10, Xx1, Xx2 eachprepared by the method as described above

<Acid Generator (B)>

B1-5: Salt represented by the formula (B1-5)

B1-21: Salt represented by the formula (B1-21)

B1-22: Salt represented by the formula (B1-22)

<Weakly Acidic Inner Salt (D)>

D1: The compound as follow, a product of Tokyo Chemical Industry Co.,LTD

<Solvent for Resist Compositions>

Propyleneglycolmonomethylether acetate 265 partsPropyleneglycolmonomethyl ether 20 parts 2-Heptanone 20 partsγ-butyrolactone 3.5 parts

<Evaluation of Resist Compositions: Negative Resist Patterns>

A composition for an organic antireflective film (“ARC-29”, by NissanChemical Co. Ltd.) was applied onto 12-inch silicon wafer and baked for60 seconds at 205° C. to form a 78 nm thick organic antireflective film.

One of the resist compositions was then applied thereon by spin coatingin such a manner that the thickness of the composition layer afterdrying (pre-baking) became 85 nm.

The obtained wafer was then pre-baked for 60 sec on a direct hot plateat the temperature given in the “PB” column in Table 1.

On the wafers on which the composition layer had thus been formed, thefilm was then exposed through a mask for forming contact-hole patterns(hole pitch 90 nm/hole diameter 55 nm) with changing exposure quantitystepwise, using an ArF excimer laser stepper for liquid-immersionlithography (“XT:1900Gi” by ASML Ltd.: NA=1.35, 3/4 Annular XY-pol.).Ultrapure water was used as medium for liquid-immersion.

After the exposure, post-exposure baking was carried out for 60 secondsat the temperature given in the “PEB” column in Table 1.

Then, development was carried out with butyl acetate (a product of TokyoChemical Industry Co., LTD) at 23° C. for 20 seconds in the manner ofdynamic dispensing method to obtain negative resist patterns.

Effective sensitivity was defined as the exposure quantity at which theresist pattern with 45 nm-hole diameter was obtained.

(Evaluation of Defects)

The above resist compositions were applied on each of the12-inch-silicon (circular shape; diameter 12 inch) wafers by spincoating so that the thickness of the resulting film became 150 nm afterdrying.

The obtained wafers were then pre-baked for 60 seconds on a direct hotplate at the temperatures given in the “PB” column in Table 1 to obtaina composition layer.

The thus obtained wafers with the produced composition layers are rinsedwith water for 60 seconds using a developing apparatus (ACT-12, Tokyoelectron Co. Ltd.).

Thereafter, the number of defects was counted using a defect inspectionapparatus (KLA-2360, KLA-Tencor Co. Ltd.)

Table 2 illustrates the results thereof.

(Critical Dimension Uniformity (CDU) Evaluation)

The resist patterns were formed in the same manner as described abovewith the exposure at the effective sensitivity. The hole diameter wasmeasured 24 times per one hole, and the average of those was determinedas its average hole diameter. The standard deviation was obtained fromthe average hole diameter based on the population which was 400 valuesof the above average hole diameter within the same wafer.

A Scanning Electron Microscope (CD SEM Hitachi CG-4000) was used for CDUevaluation.

The “◯” was given when the standard deviation was less than 1.80 nm.

The “x” was given when the standard deviation was 1.8 nm or more.

Table 2 illustrates the results thereof. The figures in parenthesesrepresent standard deviation (nm).

TABLE 2 Resist Composition Defects CDU Ex. 15 Composition 1 210 ∘(1.76)Ex. 16 Composition 2 230 ∘(1.78) Ex. 17 Composition 3 240 ∘(1.75) Ex. 18Composition 4 200 ∘(1.74) Ex. 19 Composition 5 220 ∘(1.76) Ex. 20Composition 6 200 ∘(1.74) Ex. 21 Composition 7 220 ∘(1.71) Ex. 22Composition 8 190 ∘(1.73) Ex. 23 Composition 9 200 ∘(1.74) Ex. 24Composition 10 200 ∘(1.71) Ex. 25 Composition 11 230 ∘(1.70) Ex. 26Composition 12 120 ∘(1.75) Ex. 27 Composition 13 150 ∘(1.73) Ex. 28Composition 14 300 ∘(1.75) Ex. 29 Composition 15 360 ∘(1.73) ComparativeEx. 1 Comparative Comp. 1 820 x(2.13) Comparative Ex. 2 ComparativeComp. 2 640 x(1.88)

The compound of the disclosure, and the resin which has a structuralunit derived from the compound are useful for resist compositions. Aresist composition which contains the resin shows satisfactory excellentCDU and reduced defects even after storage for a certain period.Therefore, the compound, the resin and the resist composition of thedisclosure are useful for semiconductor microfabrication.

What is claimed is:
 1. A compound which is non-ionic compound, thecompound comprising a group represented by formula (Ia):

wherein R² represents a group having a C₃ to C₁₈ alicyclic hydrocarbongroup where a methylene group may be replaced by an oxygen atom or acarbonyl group, Rf¹ and Rf² each independently represent a C₁ to C₄perfluoroalkyl group, and * represents a binding site.
 2. The compoundaccording to claim 1, which is represented by formula (I):

wherein R¹ represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom, R² represents a group having aC₃ to C₁₈ alicyclic hydrocarbon group where a methylene group may bereplaced by an oxygen atom or a carbonyl group, Rf¹ and Rf² eachindependently represent a C₁ to C₄ perfluoroalkyl group, A¹ represents asingle bond, a C₁ to C₆ alkanediyl group or**-A²-X¹-(A³-X²)_(a)-(A⁴)_(b)-, ** represents a binding site to anoxygen atom, A², A³ and A⁴ each independently represent a C₁ to C₆alkanediyl group, X¹ and X² each independently represent —O—, —CO—O— or—O—CO—, a represents 0 or 1, and b represents 0 or
 1. 3. The compoundaccording to claim 1, wherein R² is a group having a C₃ to C₁₈ alicyclichydrocarbon group.
 4. The compound according to claim 1, wherein R² is agroup having an adamantyl group where a methylene group may be replacedby an oxygen atom or a carbonyl group, or a group having a cyclohexylgroup where a methylene group may be replaced by an oxygen atom or acarbonyl group.
 5. The compound according to claim 1, wherein R² is anadamantyl group or a cyclohexyl group.
 6. The compound according toclaim 2, wherein A¹ is a C₁ to C₆ alkanediyl group or **-A²-O—CO—.
 7. Aresin comprising a structural unit derived from the compound accordingto claim
 1. 8. A resist composition comprising the resin according toclaim 7, a resin having an acid-labile group, and an acid generator: 9.A resist composition comprising the resin consisting of the structuralunit derived from the compound according to claim 1, a resin having anacid-labile group, and an acid generator:
 10. The resist compositionaccording to claim 8 comprising the resin further comprises a structuralunit represented by formula (a5-1):

wherein, R⁵¹ represents a hydrogen atom or a methyl group, R⁵²represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogen atommay be replaced by a C₁ to C₈ aliphatic hydrocarbon group or a hydroxygroup, provided that the carbon atom directly bonded to L⁵¹ has noaliphatic hydrocarbon group by which a hydrogen atom has been replaced,and L⁵¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group.
 11. The resist composition according to claim8, further comprising a salt which generates an acid weaker in aciditythan an acid generated from the acid generator.
 12. The resistcomposition according to claim 9, further comprising a salt whichgenerates an acid weaker in acidity than an acid generated from the acidgenerator.
 13. A method for producing a resist pattern comprising steps(1) to (5); (1) applying the resist composition according to claim 8onto a substrate; (2) drying the applied composition to form acomposition layer; (3) exposing the composition layer; (4) heating theexposed composition layer, and (5) developing the heated compositionlayer.
 14. A method for producing a resist pattern comprising steps (1)to (5); (1) applying the resist composition according to claim 9 onto asubstrate; (2) drying the applied composition to form a compositionlayer; (3) exposing the composition layer; (4) heating the exposedcomposition layer, and (5) developing the heated composition layer.